feat: 🎸 add functionality to message user when build fails

Dockerfile

@@ -54,6 +54,7 @@ RUN apt install \
   openssl \
   parallel \
   python3  \
+  jq \
   -y
 
 RUN curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64-${AWSCLI_VERSION}.zip" -o "awscliv2.zip"

doc/cloud-platform_environment_apply.md

@@ -41,6 +41,7 @@ $ cloud-platform environment apply -n <namespace>
       --all-namespaces          Apply all namespaces with -all-namespaces
       --batch-apply-index int   Starting index for Apply to a batch of namespaces
       --batch-apply-size int    Number of namespaces to apply in a batch
+      --build-url string        The concourse apply build url
       --cluster string          cluster context fron kubeconfig file
       --clusterdir string       folder name under namespaces/ inside cloud-platform-environments repo refering to full cluster name
       --enable-apply-skip       Enable skipping apply for a namespace

go.mod

@@ -18,10 +18,10 @@ require (
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.18.2
 	github.com/zclconf/go-cty v1.14.1
-	golang.org/x/crypto v0.18.0 // indirect
+	golang.org/x/crypto v0.19.0 // indirect
 	golang.org/x/mod v0.14.0
-	golang.org/x/net v0.20.0 // indirect
-	golang.org/x/sys v0.16.0 // indirect
+	golang.org/x/net v0.21.0 // indirect
+	golang.org/x/sys v0.17.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0
@@ -83,6 +83,7 @@ require (
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 // indirect
 	github.com/google/uuid v1.4.0 // indirect
 	github.com/gorilla/mux v1.8.0 // indirect
+	github.com/gorilla/websocket v1.5.1 // indirect
 	github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79 // indirect
 	github.com/hashicorp/errwrap v1.0.0 // indirect
 	github.com/hashicorp/go-cleanhttp v0.5.2 // indirect
@@ -120,6 +121,7 @@ require (
 	github.com/sagikazarmark/locafero v0.4.0 // indirect
 	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
 	github.com/shurcooL/graphql v0.0.0-20220606043923-3cf50f8a0a29 // indirect
+	github.com/slack-go/slack v0.12.5 // indirect
 	github.com/sourcegraph/conc v0.3.0 // indirect
 	github.com/spf13/afero v1.11.0 // indirect
 	github.com/stretchr/objx v0.5.0 // indirect
@@ -130,7 +132,7 @@ require (
 	go.uber.org/atomic v1.9.0 // indirect
 	go.uber.org/multierr v1.9.0 // indirect
 	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
-	golang.org/x/term v0.16.0 // indirect
+	golang.org/x/term v0.17.0 // indirect
 	golang.org/x/time v0.5.0 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
 	google.golang.org/protobuf v1.31.0 // indirect

go.sum

@@ -154,6 +154,8 @@ github.com/go-openapi/swag v0.21.1/go.mod h1:QYRuS/SOXUCsnplDa677K7+DxSOj6IPNl/e
 github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
 github.com/go-test/deep v1.0.3 h1:ZrJSEWsXzPOxaZnFteGEfooLba+ju3FYIbOrS+rQd68=
 github.com/go-test/deep v1.0.3/go.mod h1:wGDj63lr65AM2AQyKZd/NYHGb0R+1RLqB8NKt3aSFNA=
+github.com/go-test/deep v1.0.4 h1:u2CU3YKy9I2pmu9pX0eq50wCgjfGIt539SqR7FbHiho=
+github.com/go-test/deep v1.0.4/go.mod h1:wGDj63lr65AM2AQyKZd/NYHGb0R+1RLqB8NKt3aSFNA=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/gofrs/flock v0.8.1 h1:+gYjHKf32LDeiEEFhQaotPbLuUXjY5ZqxKgXy7n59aw=
 github.com/gofrs/flock v0.8.1/go.mod h1:F1TvTiK9OcQqauNUHlbJvyl9Qa1QvF/gOUDKA14jxHU=
@@ -211,6 +213,7 @@ github.com/google/go-cmp v0.5.1/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/
 github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.4/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.7/go.mod h1:n+brtR0CgQNWTVd5ZUFpTBC8YFBDLK/h/bpaJ8/DtOE=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
@@ -246,6 +249,8 @@ github.com/gookit/color v1.5.4/go.mod h1:pZJOeOS8DM43rXbp4AZo1n9zCU2qjpcRko0b6/Q
 github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
 github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
 github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/gorilla/websocket v1.5.1 h1:gmztn0JnHVt9JZquRuzLw3g4wouNVzKL15iLr/zn/QY=
+github.com/gorilla/websocket v1.5.1/go.mod h1:x3kM2JMyaluk02fnUJpQuwD2dCS5NDG2ZHL0uE0tcaY=
 github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79 h1:+ngKgrYPPJrOjhax5N+uePQ0Fh1Z7PheYoUI/0nzkPA=
 github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79/go.mod h1:FecbI9+v66THATjSRHfNgh1IVFe/9kFxbXtjV0ctIMA=
 github.com/grpc-ecosystem/grpc-gateway v1.16.0/go.mod h1:BDjrQk3hbvj6Nolgz8mAMFbcEtjT1g+wF4CSlocrBnw=
@@ -434,6 +439,8 @@ github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ
 github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
 github.com/skeema/knownhosts v1.2.1 h1:SHWdIUa82uGZz+F+47k8SY4QhhI291cXCpopT1lK2AQ=
 github.com/skeema/knownhosts v1.2.1/go.mod h1:xYbVRSPxqBZFrdmDyMmsOs+uX1UZC3nTN3ThzgDxUwo=
+github.com/slack-go/slack v0.12.5 h1:ddZ6uz6XVaB+3MTDhoW04gG+Vc/M/X1ctC+wssy2cqs=
+github.com/slack-go/slack v0.12.5/go.mod h1:hlGi5oXA+Gt+yWTPP0plCdRKmjsDxecdHxYQdlMQKOw=
 github.com/sourcegraph/conc v0.3.0 h1:OQTbbt6P72L20UqAkXXuLOj79LfEanQ+YQFNpLA9ySo=
 github.com/sourcegraph/conc v0.3.0/go.mod h1:Sdozi7LEKbFPqYX2/J+iBAM6HpqSLTASQIKqDmF7Mt0=
 github.com/spaolacci/murmur3 v0.0.0-20180118202830-f09979ecbc72/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2Kzu9HwQUA=
@@ -505,6 +512,8 @@ golang.org/x/crypto v0.3.1-0.20221117191849-2c476679df9a/go.mod h1:hebNnKkNXi2Uz
 golang.org/x/crypto v0.7.0/go.mod h1:pYwdfH91IfpZVANVyUOhSIPZaFoJGxTFbZhFTx+dXZU=
 golang.org/x/crypto v0.18.0 h1:PGVlW0xEltQnzFZ55hkuX5+KLyrMYhHld1YHO4AKcdc=
 golang.org/x/crypto v0.18.0/go.mod h1:R0j02AL6hcrfOiy9T4ZYp/rcWeMxM3L6QYxlOuEG1mg=
+golang.org/x/crypto v0.19.0 h1:ENy+Az/9Y1vSrlrvBSyna3PITt4tiZLf7sgCjZBX7Wo=
+golang.org/x/crypto v0.19.0/go.mod h1:Iy9bg/ha4yyC70EfRS8jz+B6ybOBKMaSxLj6P6oBDfU=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190510132918-efd6b22b2522/go.mod h1:ZjyILWgesfNpC6sMxTJOJm9Kp84zZh5NQWvqDGG3Qr8=
@@ -582,6 +591,8 @@ golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
 golang.org/x/net v0.8.0/go.mod h1:QVkue5JL9kW//ek3r6jTKnTFis1tRmNAW2P1shuFdJc=
 golang.org/x/net v0.20.0 h1:aCL9BSgETF1k+blQaYUBx9hJ9LOGP3gAVemcZlf1Kpo=
 golang.org/x/net v0.20.0/go.mod h1:z8BVo6PvndSri0LbOE3hAn0apkU+1YvI6E70E9jsnvY=
+golang.org/x/net v0.21.0 h1:AQyQV4dYCvJ7vGmJyKki9+PBdyvhkSd8EIx/qb0AYv4=
+golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
@@ -656,13 +667,17 @@ golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.16.0 h1:xWw16ngr6ZMtmxDyKyIgsE93KNKz5HKmMa3b8ALHidU=
 golang.org/x/sys v0.16.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.17.0 h1:25cE3gD+tdBA7lp7QfhuV+rJiE9YXTcS3VG1SqssI/Y=
+golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.2.0/go.mod h1:TVmDHMZPmdnySmBfhjOoOdhjzdE1h4u1VwSiw2l1Nuc=
 golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
 golang.org/x/term v0.6.0/go.mod h1:m6U89DPEgQRMq3DNkDClhWw02AUbt2daBVO4cn4Hv9U=
 golang.org/x/term v0.16.0 h1:m+B6fahuftsE9qjo0VWp2FW0mB3MTJvR0BaMQrq0pmE=
 golang.org/x/term v0.16.0/go.mod h1:yn7UURbUtPyrVJPGPq404EukNFxcm/foM+bV/bfcDsY=
+golang.org/x/term v0.17.0 h1:mkTF7LCd6WGJNL3K1Ad7kwxNfYAW6a8a8QqtMblp/4U=
+golang.org/x/term v0.17.0/go.mod h1:lLRBjIVuehSbZlaOtGMbcMncT+aqLLLmKrsjNrUguwk=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

pkg/commands/environment.go

@@ -15,8 +15,10 @@ import (
 )
 
 // variables specific to commands package used to store the values of flags of various environment sub commands
-var module, moduleVersion string
-var optFlags environment.Options
+var (
+	module, moduleVersion string
+	optFlags              environment.Options
+)
 
 // skipEnvCheck is a flag to skip the environments repository check.
 // This is useful for testing.
@@ -66,6 +68,7 @@ func addEnvironmentCmd(topLevel *cobra.Command) {
 	environmentApplyCmd.Flags().StringVar(&optFlags.ClusterCtx, "cluster", "", "cluster context fron kubeconfig file")
 	environmentApplyCmd.Flags().StringVar(&optFlags.ClusterDir, "clusterdir", "", "folder name under namespaces/ inside cloud-platform-environments repo refering to full cluster name")
 	environmentApplyCmd.PersistentFlags().BoolVar(&optFlags.RedactedEnv, "redact", true, "Redact the terraform output before printing")
+	environmentApplyCmd.Flags().StringVar(&optFlags.BuildUrl, "build-url", "", "The concourse apply build url")
 
 	environmentBumpModuleCmd.Flags().StringVarP(&module, "module", "m", "", "Module to upgrade the version")
 	environmentBumpModuleCmd.Flags().StringVarP(&moduleVersion, "module-version", "v", "", "Semantic version to bump a module to")
@@ -92,7 +95,7 @@ func addEnvironmentCmd(topLevel *cobra.Command) {
 		log.Fatal(err)
 	}
 
-	// e.g. if this is the Pull rquest to perform the apply: https://github.com/ministryofjustice/cloud-platform-environments/pull/8370, the pr ID is 8370.
+	// e.g. if this is the Pull request to perform the apply: https://github.com/ministryofjustice/cloud-platform-environments/pull/8370, the pr ID is 8370.
 	environmentPlanCmd.Flags().IntVar(&optFlags.PRNumber, "prNumber", 0, "Pull request ID or number to which you want to perform the plan")
 	environmentPlanCmd.Flags().StringVarP(&optFlags.Namespace, "namespace", "n", "", "Namespace which you want to perform the plan")
 
@@ -102,7 +105,6 @@ func addEnvironmentCmd(topLevel *cobra.Command) {
 	environmentPlanCmd.Flags().StringVar(&optFlags.ClusterCtx, "cluster", "", "cluster context fron kubeconfig file")
 	environmentPlanCmd.Flags().StringVar(&optFlags.ClusterDir, "clusterdir", "", "folder name under namespaces/ inside cloud-platform-environments repo refering to full cluster name")
 	environmentPlanCmd.PersistentFlags().BoolVar(&optFlags.RedactedEnv, "redact", true, "Redact the terraform output before printing")
-
 }
 
 var environmentCmd = &cobra.Command{
@@ -242,7 +244,6 @@ var environmentApplyCmd = &cobra.Command{
 			}
 			return
 		}
-
 	},
 }
 

pkg/environment/environmentApply.go

@@ -9,6 +9,7 @@ import (
 	gogithub "github.com/google/go-github/github"
 	"github.com/kelseyhightower/envconfig"
 	"github.com/ministryofjustice/cloud-platform-cli/pkg/github"
+	"github.com/ministryofjustice/cloud-platform-cli/pkg/slack"
 	"github.com/ministryofjustice/cloud-platform-cli/pkg/util"
 	"github.com/ministryofjustice/cloud-platform-environments/pkg/authenticate"
 	"github.com/ministryofjustice/cloud-platform-environments/pkg/namespace"
@@ -20,6 +21,7 @@ import (
 type Options struct {
 	Namespace, KubecfgPath, ClusterCtx, ClusterDir, GithubToken string
 	PRNumber                                                    int
+	BuildUrl                                                    string
 	AllNamespaces                                               bool
 	EnableApplySkip, RedactedEnv, SkipProdDestroy               bool
 	BatchApplyIndex, BatchApplySize                             int
@@ -33,6 +35,8 @@ type RequiredEnvVars struct {
 	kubernetescluster  string `required:"true" envconfig:"TF_VAR_kubernetes_cluster"`
 	githubowner        string `required:"true" envconfig:"TF_VAR_github_owner"`
 	githubtoken        string `required:"true" envconfig:"TF_VAR_github_token"`
+	slackBotToken      string `required:"false" envconfig:"SLACK_BOT_TOKEN"`
+	slackWebhookUrl    string `required:"false" envconfig:"SLACK_WEBHOOK_URL"`
 	pingdomapitoken    string `required:"true" envconfig:"PINGDOM_API_TOKEN"`
 }
 
@@ -45,6 +49,18 @@ type Apply struct {
 	GithubClient    github.GithubIface
 }
 
+func notifyUserApplyFailed(prNumberInt int, slackToken, webhookUrl, buildUrl string) {
+	if prNumberInt > 0 && strings.Contains(buildUrl, "http") {
+		prNumber := fmt.Sprintf("%d", prNumberInt)
+
+		slackErr := slack.Notify(prNumber, slackToken, webhookUrl, buildUrl)
+
+		if slackErr != nil {
+			fmt.Printf("Warning: Error notifying user of build error %v\n", slackErr)
+		}
+	}
+}
+
 // NewApply creates a new Apply object and populates its fields with values from options(which are flags),
 // instantiate Applier object which also checks and sets the Backend config variables to do terraform init,
 // RequiredEnvVars object which stores the values required for plan/apply of namespace
@@ -70,6 +86,7 @@ func (a *Apply) Initialize() {
 	a.RequiredEnvVars.kubernetescluster = reqEnvVars.kubernetescluster
 	a.RequiredEnvVars.githubowner = reqEnvVars.githubowner
 	a.RequiredEnvVars.githubtoken = reqEnvVars.githubtoken
+	a.RequiredEnvVars.slackBotToken = reqEnvVars.slackBotToken
 	a.RequiredEnvVars.pingdomapitoken = reqEnvVars.pingdomapitoken
 	// Set KUBE_CONFIG_PATH to the path of the kubeconfig file
 	// This is needed for terraform to be able to connect to the cluster when a different kubecfg is passed
@@ -84,7 +101,6 @@ func (a *Apply) Initialize() {
 // else checks for PR number and get the list of changed namespaces in the PR. Then does the `kubectl apply --dry-run=client` and
 // terraform init and plan of all the namespaces changed in the PR
 func (a *Apply) Plan() error {
-
 	if a.Options.PRNumber == 0 && a.Options.Namespace == "" {
 		return fmt.Errorf("either a PR Id/Number or a namespace is required to perform plan")
 	}
@@ -262,7 +278,6 @@ func (a *Apply) ApplyBatch() error {
 
 	repoPath := "namespaces/" + a.Options.ClusterDir
 	folderChunks, err := util.GetFolderChunks(repoPath, a.Options.BatchApplyIndex, a.Options.BatchApplySize)
-
 	if err != nil {
 		return err
 	}
@@ -365,7 +380,7 @@ func (a *Apply) applyTerraform() (string, error) {
 	return outputTerraform, nil
 }
 
-// applyTerraform calls applier -> TerraformInitAndDestroy and prints the output from applier
+// destroyTerraform calls applier -> TerraformInitAndDestroy and prints the output from applier
 func (a *Apply) destroyTerraform() (string, error) {
 	log.Printf("Running Terraform Destroy for namespace: %v", a.Options.Namespace)
 
@@ -467,6 +482,8 @@ func (a *Apply) applyNamespace() error {
 	if util.IsYamlFileExists(repoPath) {
 		outputKubectl, err := applier.applyKubectl()
 		if err != nil {
+			notifyUserApplyFailed(a.Options.PRNumber, a.RequiredEnvVars.slackBotToken, a.RequiredEnvVars.slackWebhookUrl, a.Options.BuildUrl)
+
 			return err
 		}
 
@@ -484,9 +501,9 @@ func (a *Apply) applyNamespace() error {
 	if err == nil && exists {
 		outputTerraform, err := applier.applyTerraform()
 		if err != nil {
+			notifyUserApplyFailed(a.Options.PRNumber, a.RequiredEnvVars.slackBotToken, a.RequiredEnvVars.slackWebhookUrl, a.Options.BuildUrl)
 			return err
 		}
-
 		fmt.Println("\nOutput of terraform:")
 		util.RedactedEnv(os.Stdout, outputTerraform, a.Options.RedactedEnv)
 	} else {
@@ -573,7 +590,6 @@ func (a *Apply) nsCreateRawChangedFilesInPR(cluster string, prNumber int) ([]str
 		}
 	}
 	return namespaces, nil
-
 }
 
 // nsChangedInPR get the list of changed files for a given PR. checks if the namespaces exists in the given cluster
@@ -590,7 +606,7 @@ func nsChangedInPR(files []*gogithub.CommitFile, cluster string, isDeleted bool)
 		// namespaces filepaths are assumed to come in
 		// the format: namespaces/<cluster>.cloud-platform.service.justice.gov.uk/<namespaceName>
 		s := strings.Split(*file.Filename, "/")
-		//only get namespaces from the folder that belong to the given cluster and
+		// only get namespaces from the folder that belong to the given cluster and
 		// ignore changes outside namespace directories
 		if len(s) > 1 && s[1] == cluster {
 			namespaceNames = append(namespaceNames, s[2])

pkg/slack/init.go

@@ -0,0 +1,7 @@
+package slack
+
+import "github.com/slack-go/slack"
+
+func initSlack(token string) *slack.Client {
+	return slack.New(token)
+}

pkg/slack/notifyUser.go

@@ -0,0 +1,26 @@
+package slack
+
+import (
+	"fmt"
+
+	"github.com/slack-go/slack"
+)
+
+func Notify(prNumber, token, webhookUrl, buildUrl string) error {
+	slackClient := initSlack(token)
+
+	defaultSearchParams := slack.NewSearchParameters()
+
+	results, searchErr := search(slackClient, defaultSearchParams, prNumber)
+
+	if searchErr != nil {
+		fmt.Printf("Failed to find pr in slack %v\n", searchErr)
+		return nil
+	}
+
+	// get the user who posted
+	user := results.Matches[0].User
+	ts := results.Matches[0].Timestamp
+
+	return post(user, ts, webhookUrl, buildUrl)
+}

pkg/slack/post.go

@@ -0,0 +1,21 @@
+package slack
+
+import (
+	"fmt"
+
+	"github.com/slack-go/slack"
+)
+
+func post(user, ts, webhookUrl, buildUrl string) error {
+	// https://pkg.go.dev/github.com/slack-go/slack#PostWebhook
+	message := fmt.Sprintf("<@%s> <%s|your build failed>, please address immediately or add a <https://user-guide.cloud-platform.service.justice.gov.uk/documentation/other-topics/long-running-env-operations.html|APPLY_PIPELINE_SKIP_THIS_NAMESPACE> to your namespace to prevent our pipelines from being blocked", user, buildUrl)
+
+	webhookMsg := slack.WebhookMessage{
+		Channel:         "ask-cloud-platform",
+		Text:            message,
+		ThreadTimestamp: ts,
+		ReplyBroadcast:  true,
+	}
+
+	return slack.PostWebhook(webhookUrl, &webhookMsg)
+}

pkg/slack/search.go

@@ -0,0 +1,22 @@
+package slack
+
+import (
+	"fmt"
+
+	"github.com/slack-go/slack"
+)
+
+func search(client *slack.Client, params slack.SearchParameters, query string) (*slack.SearchMessages, error) {
+	results, searchErr := client.SearchMessages(query, params)
+	if searchErr != nil {
+		fmt.Printf("Error: searching for slack messages: %v\n", searchErr.Error())
+		return nil, searchErr
+	}
+
+	if results == nil {
+		fmt.Printf("Failed to find a slack message with the PR number %s\n", query)
+		return nil, nil
+	}
+
+	return results, nil
+}