Merge ~canonical-server/prometheus-snap:prom2-update-to-latest-version into ~canonical-is-sa/prometheus-snap:prometheus2

[Lucas Kanashiro]

Update prometheus2 to version 2.20.1

Update prometheus2 snap to the latest version (2.20.1). The Server team is working on prometheus for the LMA stack we want to support, and we noticed the prometheus2 snap is quite outdated. We think we can work together with the IS team to provide and up-to-dated snap. A summary of the proposed changes:

- Update to version 2.20.1
- Build the snap based on core18
- Build the snap for different architectures: amd64, arm64, ppc64el and s390x
- Rewrite part of 'prometheus' parts section
  + Run a set of upstream tests during build time

I have personally played with it locally and AFAICS it looks good, works well. I also built the snap in all 4 architectures here:

https://code.launchpad.net/~lucaskanashiro/+snap/prometheus

Thanks for considering those changes, feedback is appreciated.

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Unable to determine commit message from repository - please click "Set commit message" and enter the commit message manually.

[Lucas Kanashiro (lucaskanashiro)]

Any feedback?

[Junien F (axino)]

LGTM, thanks a lot for doing that

review: Approve

[Tom Haddon (mthaddon)]

Two minor changes via online comments

review: Needs Fixing

[Lucas Kanashiro (lucaskanashiro)]

Thanks Junien and Tom! I added a new commit addressing Tom's comments.

[Tom Haddon (mthaddon)]

LGTM, thx

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision e9a371e4d2e296014bc79227182263be91e9a5b4

diff --git a/snapcraft.yaml b/snapcraft.yaml
index bc2afb0..908dcc3 100644
--- a/snapcraft.yaml
+++ b/snapcraft.yaml
@@ -1,10 +1,16 @@
 name: prometheus
-adopt-info: prometheus
+version: 2.20.1
+base: core18
 grade: stable
 summary: The Prometheus monitoring system and time series database
 description: |
   Prometheus is a systems and service monitoring system. It collects metrics from configured targets at given intervals, evaluates rule expressions, displays the results, and can trigger alerts if some condition is observed to be true.
 confinement: strict
+architectures:
+  - build-on: amd64
+  - build-on: arm64
+  - build-on: ppc64el
+  - build-on: s390x
 
 apps:
   prometheus:
@@ -17,31 +23,27 @@ apps:
     command: 'bin/promtool'
 plugs:
   content:
+    interface: content
     content: promreg
     target: $SNAP_DATA/promreg
 
 parts:
-  go:
-    source-tag: go1.12
   prometheus:
-    after: [go]
     plugin: go
+    go-channel: 1.14/stable
     source: https://github.com/prometheus/prometheus.git
+    source-tag: v${SNAPCRAFT_PROJECT_VERSION}
     go-importpath: github.com/prometheus/prometheus
-    build: |
-        export "GOPATH=$PWD/../go"
-        cd ../go/src/github.com/prometheus/prometheus/
-        version="$(git tag -l | grep -v '\-rc' | sort -V | tail -n 1)"
-        snap_version=$(echo $version | sed -e s/^v//)
-        snapcraftctl set-version "$snap_version"
-        git checkout tags/$version
+    build-packages: [build-essential, curl, make, npm]
+    override-build: |
+        npm install yarn -g
+        make common-test-short
         make build
-    install: |
-        mkdir $SNAPCRAFT_PART_INSTALL/bin
+        mkdir -p $SNAPCRAFT_PART_INSTALL/bin
         mkdir -p $SNAPCRAFT_PART_INSTALL/etc/prometheus
-        cp -p $SNAPCRAFT_PART_INSTALL/../src/promtool $SNAPCRAFT_PART_INSTALL/bin/
-        cp -p $SNAPCRAFT_PART_INSTALL/../src/prometheus $SNAPCRAFT_PART_INSTALL/bin/
-        cp -p $SNAPCRAFT_PART_INSTALL/../src/documentation/examples/prometheus.yml $SNAPCRAFT_PART_INSTALL/etc/prometheus/prometheus.yml.example
+        cp -p $SNAPCRAFT_PART_BUILD/promtool $SNAPCRAFT_PART_INSTALL/bin/
+        cp -p $SNAPCRAFT_PART_BUILD/prometheus $SNAPCRAFT_PART_INSTALL/bin/
+        cp -p $SNAPCRAFT_PART_SRC/documentation/examples/prometheus.yml $SNAPCRAFT_PART_INSTALL/etc/prometheus/prometheus.yml.example
   snap-wrappers:
     plugin: dump
     source: .