prep release: v1.20.0

[garypen]

Note

When approved, this PR will merge into the 1.20.0 branch which will — upon being approved itself — merge into main.

Things to review in this PR:

• Changelog correctness (There is a preview below, but it is not necessarily the most up to date. See the Files Changed for the true reality.)
• Version bumps
• That it targets the right release branch (1.20.0 in this case!).

---

🚀 Features

Configurable histogram buckets for metrics (Issue #2333)

It is now possible to change the default bucketing for histograms generated for metrics:

telemetry:
  metrics:
    common:
      buckets:
        - 0.05
        - 0.10
        - 0.25
        - 0.50
        - 1.00
        - 2.50
        - 5.00
        - 10.00
        - 20.00

By @bnjjj in #3098

🐛 Fixes

Federation v2.4.7 (Issue #3170, Issue #3133)

This release bumps the Router's Federation support from v2.4.7 to v2.4.7, which brings in notable query planner fixes from v2.4.7. Of note from those releases, this brings query planner fixes that (per that dependency's changelog):

• Re-work the code use to try to reuse query named fragments to improve performance (thus sometimes improving query (#2604) planning performance)
• Fix a raised assertion error (again, with a message of form like Cannot add selection of field X to selection set of parent type Y).
• Fix a rare issue where an interface or union field was not being queried for all the types it should be.

By @Geal in #3185

Set the global allocator in the library crate, not just the executable (Issue #3126)

In 1.19, Apollo Router switched to use jemalloc as the global Rust allocator on Linux to reduce memory fragmentation. However, prior to this change this was only occurring in the executable binary provided by the apollo-router crate and custom binaries using the crate as a library were not getting this benefit.

The apollo-router library crate now sets the global allocator so that custom binaries also take advantage of this by default. If some other choice is desired, the global-allocator Cargo feature flag can be disabled in Cargo.toml with:

[dependencies]
apollo-router = {version = "[…]", default-features = false}

Library crates that depend on apollo-router (if any) should also do this in order to leave the choice to the eventual executable. (Cargo default features are only disabled if all dependents specify default-features = false.)

By @SimonSapin in #3157

Add ca-certificates to our Docker image (Issue #3173)

We removed curl from our Docker images to improve security, which meant that our implicit install of ca-certificates (as a dependency of curl) was no longer performed.

This fix reinstates the ca-certificates package explicitly, which is required for the router to be able to process TLS requests.

By @garypen in #3174

Helm: Running of helm test no longer fails

Running helm test was generating an error since wget was sending a request without a proper body and expecting an HTTP status response of 2xx. Without the proper body, it expectedly resulted in an HTTP status of 400. By switching to using netcat (or nc) we will now check that the port is up and use that to determine that the router is functional.

By @bbardawilwiser in #3096

Move curl dependency to separate layer in Docker image (Issue #3144)

We've moved curl out of the Docker image we publish. The curl command is only used in the image we produce today for the sake of downloading dependencies. It is never used after that, but we can move it to a separate layer to further remove it from the image.

By @abernix in #3146

🛠 Maintenance

Improve cargo-about license checking (Issue #3176)

From the description of this cargo about PR, it is possible for NOASSERTION identifiers to be added when gathering license information, causing license checks to fail. This change uses the new cargo-about configuration filter-noassertion to eliminate the problem.

By @garypen in #3178

[router-perf]

CI performance tests

• const - Basic stress test that runs with a constant number of users
• no-graphos - Basic stress test, no GraphOS.
• step - Basic stress test that steps up the number of users over time
• reload - Reload test over a long period of time at a constant rate of users
• xlarge-request - Stress test with 10 MB request payload
• large-request - Stress test with a 1 MB request payload
• xxlarge-request - Stress test with 100 MB request payload