ci: fix migrate action on main

The "Migrate" GitHub action was failing intermittently due to a timing
issue. Essentially, it takes some time after the controllers/models/
machines are deployed for them to be ready to migrate. There was
previously a hardcoded wait of 20 seconds, but this is not always
enough.

The fix is to wait for everything deployed to reach a steady state
before we begin the migration. As `juju wait-for` appears to have been
removed in 4.0, I added a Bash script `.github/waitfor.sh` that allows
us to wait on `juju status` to reach a certain state (defined by a jq
query). We have to wait on:
- the source machine to become "started"
- the ubuntu/0 unit to become "idle"
- the target controller machine to become "running"

Drive-bys:
- Now that the "Generate" action is required, it must run on every
  single PR, so I've removed the path filters.
- Remove the azure provider import from the provisioner facade, and
  build juju with BUILD_TAGS='minimal provider_lxd' in the migrate
  workflow. This shaves 3-4 minutes off the build time.
- Add a debug info step to the migrate workflow, so that if there are
  future failures, we can have a baseline to debug them.

.github/waitfor.sh

@@ -0,0 +1,34 @@
+# Wait for something in 'juju status' to reach a given state
+# relevant env vars:
+# - MODEL: model to call 'juju status' in
+# - QUERY: jq query to run on the output of 'juju status'
+# - EXPECTED: what you are expecting the jq query to return
+# - JUJU_CLIENT: path to Juju client to use (default 'juju')
+# - MAX_ATTEMPTS: how many times to try (default 20)
+# - DELAY: delay between status calls in seconds (default 5)
+
+JUJU_CLIENT=${JUJU_CLIENT:-juju}
+MAX_ATTEMPTS=${MAX_ATTEMPTS:-20}
+DELAY=${DELAY:-5}
+
+attempt=0
+while true; do
+  JUJU_STATUS_CALL="$JUJU_CLIENT status --format json"
+  if [[ -n $MODEL ]]; then
+    JUJU_STATUS_CALL="$JUJU_STATUS_CALL -m $MODEL"
+  fi
+
+  STATUS=$($JUJU_STATUS_CALL | jq -r "$QUERY")
+  if [[ $STATUS == "$EXPECTED" ]]; then
+    break
+  fi
+
+  attempt=$((attempt+1))
+  if [[ "$attempt" -ge $MAX_ATTEMPTS ]]; then
+    echo "$QUERY failed"
+    exit 1
+  fi
+
+  echo "waiting for $QUERY == $EXPECTED"
+  sleep $DELAY
+done

.github/workflows/gen.yml

@@ -4,12 +4,6 @@ on:
     branches: [2.*, 3.*, 4.*, main]
   pull_request:
     types: [opened, synchronize, reopened, ready_for_review]
-    paths:
-      - '**.go'
-      - 'go.mod'
-      - '.github/workflows/gen.yml'
-      - 'Makefile'
-      - 'make_functions.sh'
   workflow_dispatch:
 
 permissions:
@@ -22,16 +16,34 @@ jobs:
     if: github.event.pull_request.draft == false
 
     steps:
+        # Since this check is marked as "required", the action needs to run on
+        # every PR. However, if there were no changes to Go files, there will
+        # be no changes to the generated files, hence we don't need to check.
+        # So this step checks which files have been changed, and allows the
+        # rest of the workflow to be skipped if no Go files were changed.
+      - name: Check changed files
+        id: should-run
+        uses: dorny/paths-filter@v3
+        with:
+          filters: |
+            go:
+              - '**.go'
+              - 'go.mod'
+              - '.github/workflows/gen.yml'
+
       - name: "Checkout"
+        if: steps.should-run.outputs.go == 'true'
         uses: actions/checkout@v4
 
       - name: "Set up Go"
+        if: steps.should-run.outputs.go == 'true'
         uses: actions/setup-go@v5
         with:
           go-version-file: 'go.mod'
           cache: true
 
       - name: "Delete all mocks"
+        if: steps.should-run.outputs.go == 'true'
         shell: bash
         # Ideally we'd delete all generated files, but we can't because some of
         # the Go code depends on generated files for go:generate to actually work.
@@ -41,6 +53,7 @@ jobs:
           done
 
       - name: "Regenerate code"
+        if: steps.should-run.outputs.go == 'true'
         shell: bash
         run: |
           # Running go generate by itself is slow over a large codebase, where
@@ -56,6 +69,7 @@ jobs:
           grep -ir "//go:generate" --include '*.go' . | awk -F : '{ print $1 }' | uniq | xargs -n 1 -P 8 -I% go generate -x $(realpath %)
 
       - name: "Check diff"
+        if: steps.should-run.outputs.go == 'true'
         shell: bash
         run: |
           git add -A

.github/workflows/migrate.yml

@@ -51,7 +51,7 @@ jobs:
 
       - name: Build local juju client
         run: |
-          make juju jujud jujud-controller &>/dev/null
+          BUILD_TAGS='minimal provider_lxd' make juju jujud jujud-controller
 
       - name: Install Juju ${{ matrix.channel }}
         if: ${{ matrix.channel != 'local' }}
@@ -96,22 +96,42 @@ jobs:
             attempt=$((attempt+1))
           done
 
-      - name: Migrate model to target controller
+      - name: Determine which Juju client to use
+        shell: bash
         run: |
-          # Determine which Juju client to use
-          JUJU='juju'
+          JUJU_CLIENT='juju'
           if [[ ${{ matrix.channel }} != 'local' ]]; then
-            JUJU='/snap/bin/juju'
+            JUJU_CLIENT='/snap/bin/juju'
           fi
+          echo "JUJU_CLIENT=$JUJU_CLIENT" >> $GITHUB_ENV
 
-          $JUJU switch source-controller
-
-          # Wait a few secs for the machine status to update
-          # so that migration prechecks pass.
-          sleep 20
+      - name: Wait for everything to reach a steady state
+        shell: bash
+        run: |
+          export JUJU_CLIENT
+          
+          # Wait for source machine to start
+          MODEL='source-controller:test-migrate' \
+          QUERY='.machines."0"."juju-status".current' EXPECTED='started' \
+          MAX_ATTEMPTS=60 ./.github/waitfor.sh
+          
+          # Wait for unit ubuntu/0 to reach idle state
+          MODEL='source-controller:test-migrate' \
+          QUERY='.applications.ubuntu.units."ubuntu/0"."juju-status".current' \
+          EXPECTED='idle' ./.github/waitfor.sh
+          
+          # Wait for target controller machine to start
+          MODEL='target-controller:controller' \
+          QUERY='.machines."0"."machine-status".current' \
+          EXPECTED='running' ./.github/waitfor.sh
 
-          $JUJU version
-          $JUJU migrate test-migrate target-controller
+      - name: Migrate model to target controller
+        shell: bash
+        run: |
+          $JUJU_CLIENT switch source-controller
+          $JUJU_CLIENT version
+          $JUJU_CLIENT status -m source-controller:test-migrate --format json || true
+          $JUJU_CLIENT migrate test-migrate target-controller
 
       - name: Check the migration was successful
         run: |
@@ -132,16 +152,6 @@ jobs:
             attempt=$((attempt+1))
             if [ "$attempt" -eq 10 ]; then
               echo "Migration timed out"
-              echo "-------------------"
-
-              echo " - Migration source controller logs"
-              juju switch source-controller
-              juju debug-log -m controller || true
-
-              echo " - Migration target controller logs"
-              juju switch target-controller
-              juju debug-log -m controller || true
-
               exit 1
             fi
           done
@@ -178,3 +188,20 @@ jobs:
             attempt=$((attempt+1))
           done
 
+      - name: Get debug info
+        if: failure()
+        run: |
+          set -x
+          echo " - Migration source status"
+          juju status -m source-controller:controller --format json || true
+          juju status -m source-controller:test-migrate --format json || true
+          
+          echo " - Migration source controller logs"
+          juju debug-log -m source-controller:controller || true
+          
+          echo " - Migration target status"
+          juju status -m target-controller:controller --format json || true
+          juju status -m target-controller:test-migrate --format json || true
+          
+          echo " - Migration target controller logs"
+          juju debug-log -m target-controller:controller || true

apiserver/facades/agent/provisioner/provisioninginfo.go

@@ -27,7 +27,6 @@ import (
 	"github.com/juju/juju/environs/simplestreams"
 	"github.com/juju/juju/environs/tags"
 	"github.com/juju/juju/internal/cloudconfig/instancecfg"
-	"github.com/juju/juju/internal/provider/azure"
 	"github.com/juju/juju/internal/storage"
 	"github.com/juju/juju/rpc/params"
 	"github.com/juju/juju/state"
@@ -446,7 +445,7 @@ func (api *ProvisionerAPI) subnetsAndZonesForSpace(ctx context.Context, machineI
 				return nil, errors.Trace(err)
 			}
 
-			if providerType != azure.ProviderType && providerType != "openstack" {
+			if providerType != "azure" && providerType != "openstack" {
 				api.logger.Warningf(warningPrefix + "no availability zone(s) set")
 				continue
 			}