Add a 'simplified mode' for configuration that can be used with only one Alertmanager instance

docs/CONFIGURATION.md

@@ -4,12 +4,12 @@
 
 By default unsee will try to read configuration file named `unsee.yaml` from
 current directory. Configuration file uses [YAML](http://yaml.org/) format and
-it needs to have `.yaml` extention.
+it needs to have `.yaml` extension.
 Custom filename and directory can be passed via command line flags or
 environment variables:
 
 * `--config.file` flag or `CONFIG_FILE` env variable - name of the config file
-  to load (without extention).
+  to load (without extension).
 * `--config.dir` flag or `CONFIG_DIR` env variable - directory where config file
   can be found.
 
@@ -36,7 +36,7 @@ $ CONFIG_FILE="example" unsee --config.dir ./docs/
 `alertmanager` section allows setting Alertmanager servers that should be
 queried for alerts.
 You can configure one or more Alertmanager servers, alerts
-with identical label set will be deduplicated and labeld with each Alertmanager
+with identical label set will be deduplicated and labeled with each Alertmanager
 server they were observed at. This allows using unsee to collect alerts from a
 pair of Alertmanager instances running in
 [HA mode](https://prometheus.io/docs/alerting/alertmanager/#high-availability).
@@ -65,15 +65,15 @@ alertmanager:
   every alert in the UI and for filtering alerts using `@alertmanager=NAME`
   filter
 * `uri` - base URI of this Alertmanager server. Supported URI schemes are
-   `http://`, `https://` and `file://`. `file://` scheme is only useful for
-   testing with JSON files, see [mock](/internal/mock/) dir for examples, files
-   in this directory are used for running tests and when running demo instance
-   of unsee with `make run`.
+  `http://`, `https://` and `file://`. `file://` scheme is only useful for
+  testing with JSON files, see [mock](/internal/mock/) dir for examples, files
+  in this directory are used for running tests and when running demo instance
+  of unsee with `make run`.
 * `timeout` - timeout for requests send to this Alertmanager server, a string in
   [time.Duration](https://golang.org/pkg/time/#ParseDuration) format.
 * `proxy` - if enabled requests from user browsers to this Alertmanager will be
-            proxied via unsee. This applies to requests made when managing
-            silences via unsee (creating or expiring silences).
+  proxied via unsee. This applies to requests made when managing
+  silences via unsee (creating or expiring silences).
 
 Example with two production Alertmanager instances running in HA mode and a
 staging instance that is also proxied:
@@ -104,11 +104,14 @@ alertmanager:
   servers: []
 ```
 
-There is no default for `alertmanager.servers` and it's a required option.
+There is no default for `alertmanager.servers` and it's a required option for
+setting multiple Alertmanager servers. For cases where only a single server
+needs to be configured without a config file see
+[Simplified Configuration](#simplified-configuration).
 
 ### Annotations
 
-`annotations` section allows configuring how alert annotation are displyed in
+`annotations` section allows configuring how alert annotation are displayed in
 the UI.
 Syntax:
 
@@ -173,7 +176,7 @@ filters:
 ```
 
 * `default` - list of filters to use by default when user navigates to unsee
-  web UI. Visit `/help` page in unsee for details on avaiable filters.
+  web UI. Visit `/help` page in unsee for details on available filters.
   Note that if a string starts with `@` YAML requires to wrap it in quotes.
 
 Example:
@@ -246,7 +249,7 @@ labels:
     - task_id
 ```
 
-Example where all but `instance` and `alertname` labels are alowed:
+Example where all but `instance` and `alertname` labels are allowed:
 
 ```yaml
 labels:
@@ -269,7 +272,7 @@ labels:
 
 ### Listen
 
-`listen` section allows configuring unsee web server behaviour.
+`listen` section allows configuring unsee web server behavior.
 Syntax:
 
 ```yaml
@@ -422,23 +425,20 @@ sentry:
 Config file options are mapped to command line flags, so `alertmanager:interval`
 config file key is accessible as `--alertmanager.interval` flag, run
 `unsee --help` to see a full list.
-Exaceptions:
+Exceptions for passing flags:
 
-* `alertmanager.servers` - this config files option is a list of maps, to
-  configure multiple Alertmanager servers config file needs to be used.
-  It's possible to pass a single Alertmanager server URI using
-  `--alertmanager.uri` flag or `ALERTMANAGER_URI` environment variable. If this
-  flag/env is used name of the Alertmanager instance will be always `default`
-  and the timeout will be set to `40s`, customizing those two options requires
-  config file.
-* `jira` - this option is a list of maps and it's only avaiable when using
+* `jira` - this option is a list of maps and it's only available when using
   config file.
 
+There's no support for configuring multiple Alertmanager servers using
+flags, but it's possible to configure a single Alertmanager instance this way,
+see the [Simplified Configuration](#simplified-configuration) section.
+
 ## Environment variables
 
-Environment variables are mapped in a similiar way as command line flags,
+Environment variables are mapped in a similar way as command line flags,
 `alertmanager:interval` is accessible as `ALERTMANAGER_INTERVAL` env.
-Same exceptions apply as with command line flags.
+Exceptions for passing flags:
 
 * `HOST` - used by gin webserver, same effect as setting `listen:address` config
   option
@@ -446,3 +446,59 @@ Same exceptions apply as with command line flags.
   option
 * `SENTRY_DSN` - is used by Sentry itself, same effect as passing value to
   `sentry:private` config option.
+
+There's no support for configuring multiple alertmanager servers using
+environment variables, but it's possible to configure a single Alertmanager
+instance this way, see the [Simplified Configuration](#simplified-configuration)
+section.
+
+## Simplified Configuration
+
+To configure multiple Alertmanager instances unsee requires a config file, but
+for a single Alertmanager instance cases it's possible to configure all
+Alertmanager server options that are set for `alertmanager.servers` config
+section using only flags or environment variables.
+
+### Alertmanager URI
+
+To set the `uri` key from `alertmanager.servers` map `ALERTMANAGER_URI` env or
+`--alertmanager.uri` flag can be used.
+Example:
+
+```
+$ ALERTMANAGER_URI=https://alertmanager.example.com unsee
+$ unsee --alertmanager.uri https://alertmanager.example.com
+```
+
+### Alertmanager name
+
+To set the `name` key from `alertmanager.servers` map `ALERTMANAGER_NAME` env or
+`--alertmanager.name` flag can be used.
+Example:
+
+```
+$ ALERTMANAGER_NAME=single unsee
+$ unsee --alertmanager.name single
+```
+
+### Alertmanager timeout
+
+To set the `timeout` key from `alertmanager.servers` map `ALERTMANAGER_TIMEOUT`
+env or `--alertmanager.timeout` flag can be used.
+Example:
+
+```
+$ ALERTMANAGER_TIMEOUT=10s unsee
+$ unsee --alertmanager.timeout 10s
+```
+
+### Alertmanager request proxy
+
+To set the `proxy` key from `alertmanager.servers` map `ALERTMANAGER_PROXY`
+env or `--alertmanager.proxy` flag can be used.
+Example:
+
+```
+$ ALERTMANAGER_PROXY=true unsee
+$ unsee --alertmanager.proxy
+```

internal/config/config.go

@@ -21,9 +21,16 @@ var (
 )
 
 func init() {
-	pflag.String("alertmanager.uri", "", "Alertmanager server URI")
-	pflag.Duration("alertmanager.interval", time.Second*60,
+	pflag.Duration("alertmanager.interval", time.Minute,
 		"Interval for fetching data from Alertmanager servers")
+	pflag.String("alertmanager.name", "default",
+		"Name for the Alertmanager server (only used with simplified config)")
+	pflag.String("alertmanager.uri", "",
+		"Alertmanager server URI (only used with simplified config)")
+	pflag.Duration("alertmanager.timeout", time.Second*40,
+		"Timeout for requests sent to the Alertmanager server (only used with simplified config)")
+	pflag.Bool("alertmanager.proxy", false,
+		"Proxy all client requests to Alertmanager via unsee (only used with simplified config)")
 
 	pflag.Bool(
 		"annotations.default.hidden", false,
@@ -106,6 +113,7 @@ func (config *configSchema) Read() {
 		log.Infof("Config file used: %s", v.ConfigFileUsed())
 	}
 
+	config.Alertmanager.Servers = []alertmanagerConfig{}
 	config.Alertmanager.Interval = v.GetDuration("alertmanager.interval")
 	config.Annotations.Default.Hidden = v.GetBool("annotations.default.hidden")
 	config.Annotations.Hidden = v.GetStringSlice("annotations.hidden")
@@ -141,11 +149,13 @@ func (config *configSchema) Read() {
 
 	// accept single Alertmanager server from flag/env if nothing is set yet
 	if len(config.Alertmanager.Servers) == 0 && v.GetString("alertmanager.uri") != "" {
+		log.Info("Using simple config with a single Alertmanager server")
 		config.Alertmanager.Servers = []alertmanagerConfig{
 			alertmanagerConfig{
-				Name:    "default",
+				Name:    v.GetString("alertmanager.name"),
 				URI:     v.GetString("alertmanager.uri"),
-				Timeout: time.Second * 40,
+				Timeout: v.GetDuration("alertmanager.timeout"),
+				Proxy:   v.GetBool("alertmanager.proxy"),
 			},
 		}
 	}

internal/config/config_test.go

@@ -3,6 +3,7 @@ package config
 import (
 	"os"
 	"testing"
+	"time"
 
 	"github.com/pmezard/go-difflib/difflib"
 
@@ -16,6 +17,10 @@ func resetEnv() {
 	unseeEnvVariables := []string{
 		"ALERTMANAGER_INTERVAL",
 		"ALERTMANAGER_URI",
+		"ALERTMANAGER_URIS",
+		"ALERTMANAGER_NAME",
+		"ALERTMANAGET_TIMEOUT",
+		"ALERTMANAGER_TTL",
 		"ANNOTATIONS_DEFAULT_HIDDEN",
 		"ANNOTATIONS_HIDDEN",
 		"ANNOTATIONS_VISIBLE",
@@ -165,6 +170,31 @@ func TestReadConfig(t *testing.T) {
 	testReadConfig(t)
 }
 
+func TestReadSimpleConfig(t *testing.T) {
+	resetEnv()
+	log.SetLevel(log.ErrorLevel)
+	os.Setenv("ALERTMANAGER_URI", "http://localhost")
+	os.Setenv("ALERTMANAGER_NAME", "single")
+	os.Setenv("ALERTMANAGER_TIMEOUT", "15s")
+	os.Setenv("ALERTMANAGER_PROXY", "true")
+	os.Setenv("ALERTMANAGER_INTERVAL", "3m")
+	Config.Read()
+	if len(Config.Alertmanager.Servers) != 1 {
+		t.Errorf("Expected 1 Alertmanager server, got %d", len(Config.Alertmanager.Servers))
+	} else {
+		am := Config.Alertmanager.Servers[0]
+		if am.Name != "single" {
+			t.Errorf("Expect Alertmanager name 'single' got '%s'", am.Name)
+		}
+		if am.Timeout != time.Second*15 {
+			t.Errorf("Expect Alertmanager timeout '%v' got '%v'", time.Second*15, am.Timeout)
+		}
+		if Config.Alertmanager.Interval != time.Minute*3 {
+			t.Errorf("Expect Alertmanager timeout '%v' got '%v'", time.Minute*3, Config.Alertmanager.Interval)
+		}
+	}
+}
+
 type urlSecretTest struct {
 	raw       string
 	sanitized string