This adds test coverage for 'compute_ctl', as it is now used by all
the python tests.
There are a few differences in how 'compute_ctl' is called in the
tests, compared to the real web console:
- In the tests, the postgresql.conf file is included as one large
string in the spec file, and it is written out as it is to the data
directory. I added a new field for that to the spec file. The real
web console, however, sets all the necessary settings in the
'settings' field, and 'compute_ctl' creates the postgresql.conf from
those settings.
- In the tests, the information needed to connect to the storage, i.e.
tenant_id, timeline_id, connection strings to pageserver and
safekeepers, are now passed as new fields in the spec file. The real
web console includes them as the GUCs in the 'settings' field. (Both
of these are different from what the test control plane used to do:
It used to write the GUCs directly in the postgresql.conf file). The
plan is to change the control plane to use the new method, and
remove the old method, but for now, support both.
Some tests that were sensitive to the amount of WAL generated needed
small changes, to accommodate that compute_ctl runs the background
health monitor which makes a few small updates. Also some tests shut
down the pageserver, and now that the background health check can run
some queries while the pageserver is down, that can produce a few
extra errors in the logs, which needed to be allowlisted.
Other changes:
- remove obsolete comments about PostgresNode;
- create standby.signal file for Static compute node;
- log output of `compute_ctl` and `postgres` is merged into
`endpoints/compute.log`.
---------
Co-authored-by: Anastasia Lubennikova <anastasia@neon.tech>
This parameter can be use to restrict number of image layers generated
because of GC request (wanted image layers).
Been set to zero it completely eliminates creation of such image layers.
So it allows to avoid extra storage consumption after merging #3673
## Problem
PR #3673 forces generation of missed image layers. So i short term is
cause cause increase (in worst case up to two times) size of storage.
It was intended (by me) that GC period is comparable with PiTR interval.
But looks like it is not the case now - GC is performed much more
frequently. It may cause the problem with space exhaustion: GC forces
new image creation while large PiTR still prevent GC from collecting old
layers.
## Summary of changes
Add new pageserver parameter` forced_image_creation_limit` which
restrict number of created image layers which are requested by GC.
## Checklist before requesting a review
- [ ] I have performed a self-review of my code.
- [ ] If it is a core feature, I have added thorough tests.
- [ ] Do we need to implement analytics? if so did you add the relevant
metrics to the dashboard?
- [ ] If this PR requires public announcement, mark it with
/release-notes label and add several sentences in this section.
## Checklist before merging
- [ ] Do not forget to reformat commit message to not include the above
checklist
We used to generate the ID, if the caller didn't specify it. That's bad
practice, however, because network is never fully reliable, so it's
possible we create a new tenant but the caller doesn't know about it,
and because it doesn't know the tenant ID, it has no way of retrying or
checking if it succeeded. To discourage that, make it mandatory. The web
control plane has not relied on the auto-generation for a long time.
This PR enforces that the tenant create / update-config APIs reject
requests with unknown fields.
This is a desirable property because some tenant config settings control
the lifetime of user data (e.g., GC horizon or PITR interval).
Suppose we inadvertently rename the `pitr_interval` field in the Rust
code.
Then, right now, a client that still uses the old name will send a
tenant config request to configure a new PITR interval.
Before this PR, we would accept such a request, ignore the old name
field, and use the pageserver.toml default value for what the new PITR
interval is.
With this PR, we will instead reject such a request.
One might argue that the client could simply check whether the config it
sent has been applied, using the `/v1/tenant/.../config` endpoint.
That is correct for tenant create and update-config.
But, attach will soon [^1] grow the ability to have attach-time config
as well.
If we ignore unknown fields and fall back to global defaults in that
case, we risk data loss.
Example:
1. Default PITR in pageservers is 7 days.
2. Create a tenant and set its PITR to 30 days.
3. For 30 days, fill the tenant continuously with data.
4. Detach the tenant.
5. Attach tenant.
Attach must use the 30-day PITR setting in this scenario.
If it were to fall back to the 7-day default value, we would lose 23
days of PITR capability for the tenant.
So, the PR that adds attach-time tenant config will build on the
(clunky) infrastructure added in this PR
[^1]: https://github.com/neondatabase/neon/pull/4255
Implementation Notes
====================
This could have been a simple `#[serde(deny_unknown_fields)]` but sadly,
that is documented- but silent-at-compile-time-incompatible with
`#[serde(flatten)]`. But we are still using this by adding on outer struct and use unit tests to ensure it is correct.
`neon_local tenant config` now uses the `.remove()` pattern + bail if
there are leftover config args. That's in line with what
`neon_local tenant create` does. We should dedupe that logic in a future
PR.
---------
Signed-off-by: Alex Chi <iskyzh@gmail.com>
Co-authored-by: Alex Chi <iskyzh@gmail.com>
This is prep for https://github.com/neondatabase/neon/pull/4255
[1/X] OpenAPI: share a single definition of TenantConfig
DRYs up the pageserver OpenAPI YAML's representation of
tenant config.
All the fields of tenant config are now located in a model schema
called TenantConfig.
The tenant create & config-change endpoints have separate schemas,
TenantCreateInfo and TenantConfigureArg, respectively.
These schemas inherit from TenantConfig, using allOf 1.
The tenant config-GET handler's response was previously named
TenantConfig.
It's now named TenantConfigResponse.
None of these changes affect how the request looks on the wire.
The generated Go code will change for Console because the OpenAPI code
generator maps `allOf` to a Go struct embedding.
Luckily, usage of tenant config in Console is still very lightweigt,
but that will change in the near future.
So, this is a good chance to set things straight.
The console changes are tracked in
https://github.com/neondatabase/cloud/pull/5046
[2/x]: extract the tenant config parts of create & config requests
[3/x]: code movement: move TenantConfigRequestConfig next to
TenantCreateRequestConfig
[4/x] type-alias TenantConfigRequestConfig = TenantCreateRequestConfig;
They are exactly the same.
[5/x] switch to qualified use for tenant create/config request api
models
[6/x] rename models::TenantConfig{RequestConfig,} and remove the alias
[7/x] OpenAPI: sync tenant create & configure body names from Rust code
[8/x]: dedupe the two TryFrom<...> for TenantConfOpt impls
The only difference is that the TenantConfigRequest impl does
```
tenant_conf.max_lsn_wal_lag = request_data.max_lsn_wal_lag;
tenant_conf.trace_read_requests = request_data.trace_read_requests;
```
and the TenantCreateRequest impl does
```
if let Some(max_lsn_wal_lag) = request_data.max_lsn_wal_lag {
tenant_conf.max_lsn_wal_lag = Some(max_lsn_wal_lag);
}
if let Some(trace_read_requests) = request_data.trace_read_requests {
tenant_conf.trace_read_requests = Some(trace_read_requests);
}
```
As far as I can tell, these are identical.
It's more convenient than parsing the postgresql.conf file.
Extracted from PR #3886. I started working on another patch (to make it
safe to run two "neon_local endpoint create" commands concurrently), and
realized that this change will make that simpler too.
Notes:
- This still needs UI support from the Console
- I've not tuned any GUCs for PostgreSQL to make this work better
- Safekeeper has gotten a tweak in which WAL is sent and how: It now
sends zero-ed WAL data from the start of the timeline's first segment up to
the first byte of the timeline to be compatible with normal PostgreSQL
WAL streaming.
- This includes the commits of #3714
Fixes one part of https://github.com/neondatabase/neon/issues/769
Co-authored-by: Anastasia Lubennikova <anastasia@neon.tech>
And add corresponding unit test.
The fix is to use `.remove()` instead of `.get()` when processing the
arugments hash map.
The code uses emptiness of the hash map to determine whether all
arguments have been processed.
This was likely a copy-paste error.
refs https://github.com/neondatabase/neon/issues/3942
Before this patch, if a tenant would override its eviction_policy
setting to use a lower LayerAccessThreshold::threshold than the
`evictions_low_residence_duration_metric_threshold`, the evictions done
for that tenant would count towards the
`evictions_with_low_residence_duration` metric.
That metric is used to identify pre-mature evictions, commonly triggered
by disk-usage-based eviction under disk pressure.
We don't want that to happen for the legitimate evictions of the tenant
that overrides its eviction_policy.
So, this patch
- moves the setting into TenantConf
- adds test coverage
- updates the staging & prod yamls
Forward Compatibility:
Software before this patch will ignore the new tenant conf field and use
the global one instead.
So we can roll back safely.
Backward Compatibility:
Parsing old configs with software as of this patch will fail in
`PageServerConf::parse_and_validate` with error
`unrecognized pageserver option 'evictions_low_residence_duration_metric_threshold'`
if the option is still present in the global section.
We deal with this by updating the configs in Ansible.
fixes https://github.com/neondatabase/neon/issues/3940
We use the term "endpoint" in for compute Postgres nodes in the web UI
and user-facing documentation now. Adjust the nomenclature in the code.
This changes the name of the "neon_local pg" command to "neon_local
endpoint". Also adjust names of classes, variables etc. in the python
tests accordingly.
This also changes the directory structure so that endpoints are now
stored in:
.neon/endpoints/<endpoint id>
instead of:
.neon/pgdatadirs/tenants/<tenant_id>/<endpoint (node) name>
The tenant ID is no longer part of the path. That means that you
cannot have two endpoints with the same name/ID in two different
tenants anymore. That's consistent with how we treat endpoints in the
real control plane and proxy: the endpoint ID must be globally unique.
Instead of checking neon.safekeepers GUC value in existing pg node data dir,
just always run sync-safekeepers when safekeepers are configured. Without this
change, creation of new compute didn't run it. That's ok for new
timeline/branch (it doesn't return anything useful anyway, and LSN is known by
pageserver), but restart of compute for existing timeline bore the risk of
getting basebackup not on the latest LSN, i.e. basically broken -- it might not
have prev_lsn, and even if it had, walproposer would complain anyway.
fixes https://github.com/neondatabase/neon/issues/2963
This patch adds a pageserver-global background loop that evicts layers
in response to a shortage of available bytes in the $repo/tenants
directory's filesystem.
The loop runs periodically at a configurable `period`.
Each loop iteration uses `statvfs` to determine filesystem-level space
usage. It compares the returned usage data against two different types
of thresholds. The iteration tries to evict layers until app-internal
accounting says we should be below the thresholds. We cross-check this
internal accounting with the real world by making another `statvfs` at
the end of the iteration. We're good if that second statvfs shows that
we're _actually_ below the configured thresholds. If we're still above
one or more thresholds, we emit a warning log message, leaving it to the
operator to investigate further.
There are two thresholds:
- `max_usage_pct` is the relative available space, expressed in percent
of the total filesystem space. If the actual usage is higher, the
threshold is exceeded.
- `min_avail_bytes` is the absolute available space in bytes. If the
actual usage is lower, the threshold is exceeded.
The iteration evicts layers in LRU fashion with a reservation of up to
`tenant_min_resident_size` bytes of the most recent layers per tenant.
The layers not part of the per-tenant reservation are evicted
least-recently-used first until we're below all thresholds. The
`tenant_min_resident_size` can be overridden per tenant as
`min_resident_size_override` (bytes).
In addition to the loop, there is also an HTTP endpoint to perform one
loop iteration synchronous to the request. The endpoint takes an
absolute number of bytes that the iteration needs to evict before
pressure is relieved. The tests use this endpoint, which is a great
simplification over setting up loopback-mounts in the tests, which would
be required to test the statvfs part of the implementation. We will rely
on manual testing in staging to test the statvfs parts.
The HTTP endpoint is also handy in emergencies where an operator wants
the pageserver to evict a given amount of space _now. Hence, it's
arguments documented in openapi_spec.yml. The response type isn't
documented though because we don't consider it stable. The endpoint
should _not_ be used by Console but it could be used by on-call.
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
Co-authored-by: Dmitry Rodionov <dmitry@neon.tech>
Co-authored-by: Heikki Linnakangas <heikki@neon.tech>
whoami() was never called, 'is_test' was never set.
'restart()' might be useful, but it wasn't hooked up the CLI so it was
dead code. It's not clear what kind of a restart it should perform,
anyway: just restart Postgres, or re-initialize the data directory
from a fresh basebackup like "stop"+"start" does.
- Remove the neon.safekeeper_token_env GUC. It was used to set the
name of an environment variable, which was then used in pageserver
and safekeeper connection strings to in place of the
password. Instead, always look up the environment variable called
NEON_AUTH_TOKEN. That's what neon.safekeeper_token_env was always
set to in practice, and I don't see the need for the extra level of
indirection or configurability.
- Instead of substituting $NEON_AUTH_TOKEN in the connection strings,
pass $NEON_AUTH_TOKEN "out-of-band" as the password, when we connect
to the pageserver or safekeepers. That's simpler.
- Also use the password from $NEON_AUTH_TOKEN in compute_ctl, when it
connects to the pageserver to get the "base backup".
The control plane currently only supports EdDSA. We need to either teach
the storage to use EdDSA, or the control plane to use RSA. EdDSA is more
modern, so let's use that.
We could support both, but it would require a little more code and tests,
and we don't really need the flexibility since we control both sides.
This allows you to run without the 'openssl' binary as long as you
don't enable authentication. This becomes more important with the next
commit, which switches the JWT algorithm to EdDSA. LibreSSL does not
support EdDSA, and LibreSSL comes with macOS, so the next commit makes
it much more likely for the key generation to fail for macOS users.
To allow running without a keypair, don't generate the authentication
token in the 'neon_local init' step. Instead, generate a new token on
every request that needs one, using the private key.
Create `safekeeper_pg_io_bytes_total` metric to track total amount of
bytes written/read in a postgres connections to safekeepers. This metric
has the following labels:
- `client_az` – availability zone of the connection initiator, or
`"unknown"`
- `sk_az` – availability zone of the safekeeper, or `"unknown"`
- `app_name` – `application_name` of the postgres client
- `dir` – data direction, either `"read"` or `"write"`
- `same_az` – `"true"`, `"false"` or `"unknown"`. Can be derived from
`client_az` and `sk_az`, exists purely for convenience.
This is implemented by passing availability zone in the connection
string, like this: `-c tenant_id=AAA timeline_id=BBB
availability-zone=AZ-1`.
Update ansible deployment scripts to add availability_zone argument
to safekeeper and pageserver in systemd service files.
This makes it possible to enable authentication only for the mgmt HTTP
API or the compute API. The HTTP API doesn't need to be directly
accessible from compute nodes, and it can be secured through network
policies. This also allows rolling out authentication in a piecemeal
fashion.
- Add support for splitting async postgres_backend into read and write halfes.
Safekeeper needs this for bidirectional streams. To this end, encapsulate
reading-writing postgres messages to framed.rs with split support without any
additional changes (relying on BufRead for reading and BytesMut out buffer for
writing).
- Use async postgres_backend throughout safekeeper (and in proxy auth link
part).
- In both safekeeper COPY streams, do read-write from the same thread/task with
select! for easier error handling.
- Tidy up finishing CopyBoth streams in safekeeper sending and receiving WAL
-- join split parts back catching errors from them before returning.
Initially I hoped to do that read-write without split at all, through polling
IO:
https://github.com/neondatabase/neon/pull/3522
However that turned out to be more complicated than I initially expected
due to 1) borrow checking and 2) anon Future types. 1) required Rc<Refcell<...>>
which is Send construct just to satisfy the checker; 2) can be workaround with
transmute. But this is so messy that I decided to leave split.
This patch adds a per-timeline periodic task that executes an eviction
policy. The eviction policy is configurable per tenant.
Two policies exist:
- NoEviction (the default one)
- LayerAccessThreshold
The LayerAccessThreshold policy examines the last access timestamp per
layer in the layer map and evicts the layer if that last access is
further in the past than a configurable threshold value.
This policy kind is evaluated periodically at a configurable period.
It logs a summary statistic at `info!()` or `warn!()` level, depending
on whether any evictions failed.
This feature has no explicit killswitch since it's off by default.
This reverts commit 826e89b9ce.
The problem with that commit was that it deletes the TempDir while
there are still EphemeralFile instances open.
At first I thought this could be fixed by simply adding
Handle::current().block_on(task_mgr::shutdown(None, Some(tenant_id), None))
to TenantHarness::drop, but it turned out to be insufficient.
So, reverting the commit until we find a proper solution.
refs https://github.com/neondatabase/neon/issues/3385
Follow-up of https://github.com/neondatabase/neon/pull/3270 which made
an example from main README.md not working.
Fixes that, by adding a way to specify a default tenant now and modifies
the basic neon_local test to start postgres and check branching.
Not all neon_local commands are implemented, so not all README.md
contents is tested yet.
For every Python test, we start the storage first, and expect that
later, in the test, when we start a compute, it will work without
specific timeline and tenant creation or their IDs specified.
For that, we have a concept of "default" branch that was created on the
control plane level first, but that's not needed at all, given that it's
only Python tests that need it: let them create the initial timeline
during set-up.
Before, control plane started and stopped pageserver for timeline
creation, now Python harness runs an extra tenant creation request on
test env init.
I had to adjust the metrics test, turns out it registered the metrics
from the default tenant after an extra pageserver restart.
New model does not sent the metrics before the collection time happens,
and that was 30s before.
Changes are:
* Pageserver: start reading from NEON_AUTH_TOKEN by default.
Warn if ZENITH_AUTH_TOKEN is used instead.
* Compute, Docs: fix the default token name.
* Control plane: change name of the token in configs and start
sequences.
Compatibility:
* Control plane in tests: works, no compatibility expected.
* Control plane for local installations: never officially supported
auth anyways. If someone did enable it, `pageserver.toml` should be updated
with the new `neon.pageserver_connstring` and `neon.safekeeper_token_env`.
* Pageserver is backward compatible: you can run new Pageserver with old
commands and environment configurations, but not vice-versa.
The culprit is the hard-coded `NEON_AUTH_TOKEN`.
* Compute has no code changes. As long as you update its configuration
file with `pageserver_connstring` in sync with the start up scripts,
you are good to go.
* Safekeeper has no code changes and has never used `ZENITH_AUTH_TOKEN` in
the first place.
1.66 release speeds up compile times for over 10% according to tests.
Also its Clippy finds plenty of old nits in our code:
* useless conversion, `foo as u8` where `foo: u8` and similar, removed
`as u8` and similar
* useless references and dereferenced (that were automatically adjusted
by the compiler), removed various `&` and `*`
* bool -> u8 conversion via `if/else`, changed to `u8::from`
* Map `.iter()` calls where only values were used, changed to
`.values()` instead
Standing out lints:
* `Eq` is missing in our protoc generated structs. Silenced, does not
seem crucial for us.
* `fn default` looks like the one from `Default` trait, so I've
implemented that instead and replaced the `dummy_*` method in tests with
`::default()` invocation
* Clippy detected that
```
if retry_attempt < u32::MAX {
retry_attempt += 1;
}
```
is a saturating add and proposed to replace it.
This fixes all kinds of problems related to missing params,
like broken timestamps (due to `integer_datetimes`).
This solution is not ideal, but it will help. Meanwhile,
I'm going to dedicate some time to improving connection machinery.
Note that this **does not** fix problems with passing certain parameters
in a reverse direction, i.e. **from client to compute**. This is a
separate matter and will be dealt with in an upcoming PR.
Removes the race during pageserver initial timeline creation that lead to partial layer uploads.
This race is only reproducible in test code, we do not create initial timelines in cloud (yet, at least), but still nice to remove the non-deterministic behavior.
This patch centralize the logic of creating & reading pid files into the
new pid_file module and improves upon / makes explicit a few race conditions
that existed with the previous code.
Starting Processes / Creating Pidfiles
======================================
Before this patch, we had three places that had very similar-looking
match lock_file::create_lock_file { ... }
blocks.
After this change, they can use a straight-forward call provided
by the pid_file:
pid_file::claim_pid_file_for_pid()
Stopping Processes / Reading Pidfiles
=====================================
The new pid_file module provides a function to read a pidfile,
called read_pidfile(), that returns a
pub enum PidFileRead {
NotExist,
NotHeldByAnyProcess(PidFileGuard),
LockedByOtherProcess(Pid),
}
If we get back NotExist, there is nothing to kill.
If we get back NotHeldByAnyProcess, the pid file is stale and we must
ignore its contents.
If it's LockedByOtherProcess, it's either another pidfile reader
or, more likely, the daemon that is still running.
In this case, we can read the pid in the pidfile and kill it.
There's still a small window where this is racy, but it's not a
regression compared to what we have before.
The NotHeldByAnyProcess is an improvement over what we had before
this patch. Before, we would blindly read the pidfile contents
and kill, even if no other process held the flock.
If the pidfile was stale (NotHeldByAnyProcess), then that kill
would either result in ESRCH or hit some other unrelated process
on the system. This patch avoids the latter cacse by grabbing
an exclusive flock before reading the pidfile, and returning the
flock to the caller in the form of a guard object, to avoid
concurrent reads / kills.
It's hopefully irrelevant in practice, but it's a little robustness
that we get for free here.
Maintain flock on Pidfile of ETCD / any InitialPidFile::Create()
================================================================
Pageserver and safekeeper create their pidfiles themselves.
But for etcd, neon_local creates the pidfile (InitialPidFile::Create()).
Before this change, we would unlock the etcd pidfile as soon as
`neon_local start` exits, simply because no-one else kept the FD open.
During `neon_local stop`, that results in a stale pid file,
aka, NotHeldByAnyProcess, and it would henceforth not trust that
the PID stored in the file is still valid.
With this patch, we make the etcd process inherit the pidfile FD,
thereby keeping the flock held until it exits.
Our shutdown procedure for "pageserver init" was buggy. Firstly, it
merely sent the process a SIGKILL, but did not wait for it to actually
exit. Normally, it should exit quickly as SIGKILL cannot be caught or
ignored by the target process, but it's still asynchronous and the
process can still be alive when the kill(2) call returns. Secondly,
"neon_local" removed the PID file after sending SIGKILL, even though the
process was still running. That hid the first problem: if we didn't
remove the PID file, and you start a new pageserver process while the
old one is still running, you would get an error when the new process
tries to lock the PID file.
We've been seeing a lot of "Cannot assign requested address" failures in
the CI lately. Our theory is that when we run "pageserver init"
immediately followed by "pageserver start", the first process is still
running and listening on the port when the second invocation starts up.
This commit hopefully fixes the problem.
It is generally a bad idea for the "neon_local" to remove the PID file
on the child process's behalf. The correct way would be for the server
process to remove the PID file, after it has fully shutdown everything
else. We don't currently have a robust way to ensure that everything has
truly shut down and closed, however.
A simpler way is to simply never remove the PID file. It's not necessary
to remove the PID file for correctness: we cannot rely on the cleanup to
happen anyway, if the server process crashes for example. Because of
that, we already have all the logic in place to deal with a stale PID
file that belonged to a process that already exited. Let's rely on that
on normal shutdown too.
Nothing interesting in these changes. Passing through the
RUST_BACKTRACE=full will hopefully save someone else panick reproduction
time.
Co-authored-by: Heikki Linnakangas <heikki@neon.tech>
* Fix https://github.com/neondatabase/neon/issues/1854
* Never log Safekeeper::conninfo in walproposer as it now contains a secret token
* control_panel, test_runner: generate and pass JWT tokens for Safekeeper to compute and pageserver
* Compute: load JWT token for Safekepeer from the environment variable. Do not reuse the token from
pageserver_connstring because it's embedded in there weirdly.
* Pageserver: load JWT token for Safekeeper from the environment variable.
* Rewrite docs/authentication.md
Downsides are:
* We store all components of the config separately. `Url` stores them inside a single
`String` and a bunch of ints which point to different parts of the URL, which is
probably more efficient.
* It is now impossible to pass arbitrary connection strings to the configuration file,
one has to support all components explicitly. However, we never supported anything
except for `host:port` anyway.
Upsides are:
* This significantly restricts the space of possible connection strings, some of which
may be either invalid or unsupported. E.g. Postgres' connection strings may include
a bunch of parameters as query (e.g. `connect_timeout=`, `options=`). These are nether
validated by the current implementation, nor passed to the postgres client library,
Hence, storing separate fields expresses the intention better.
* The same connection configuration may be represented as a URL in multiple ways
(e.g. either `password=` in the query part or a standard URL password).
Now we have a single canonical way.
* Escaping is provided for `options=`.
Other possibilities considered:
* `newtype` with a `String` inside and some validation on creation.
This is more efficient, but harder to log for two reasons:
* Passwords should never end up in logs, so we have to somehow
* Escaped `options=` are harder to read, especially if URL-encoded,
and we use `options=` a lot.
- Pass through FAILPOINTS environment variable to the pageserver in
"neon_local pageserver start" command
- On startup, list any failpoints that were set with FAILPOINTS to the log
- Add optional "extra_env_vars" argument to the NeonPageserver.start()
function in the python fixture, so that you can pass FAILPOINTS
None of the tests use this functionality yet; that comes in a separate
commit.
closes https://github.com/neondatabase/neon/pull/2865
* Poll more frequently when waiting for process start/stop. This
speeds up startup and shutdown in tests. We did this already in
commit 52ce1c9d53, which reduced the interval to 100 ms, but it was
inadvertently increased back to 500 ms in commit d42700280f. Reduce
it to 100 ms again, for both start and stop operations.
* Harmonize the start and stop loops, printing the dots and notices
the same way in both. I considered extracting the logic to a
separate retry-function that takes a closure as argument that does
the polling, but as long as we only have two copies, the code
duplication isn't that bad.
* Remove newline after "Starting pageserver" and "Starting etcd"
messages, so that the progress-indicator dots that are printed once
a second are printed on the same line. Before:
Starting pageserver at '127.0.0.1:64000' in '.neon'
...
pageserver started, pid: 2538937
After:
Starting pageserver at '127.0.0.1:64000' in '.neon'...
pageserver started, pid: 2538937
The "Starting safekeeper" message already got this right.
* Update example output in README.md to match
