Adopt existing channel on create (#113)

* Adopt existing channel on create
If a new 'adopt_existing_channel' attribute is set 'true' (default 'false'
for backwards compatibility), an existing channel with the same name
and type will be 'adopted' by the terraform provider, and unarchived
if necessary, to serve as the newly 'created' channel.
This brings parity with the existing provider functionality of archiving
or abandoning channels on terraform resource destroy. Now you can do
a 'terraform apply', 'terraform destroy', and 'terraform apply' again
without errors.

* Make sure api user is in the channel before doing channel
membership operations (needed when adopting existing unarchived
channels)

* Update to terraform-plugin-log v0.4.0
The upstream provider updated the sdk version, which pulled in this
new version. The new version has breaking API changes to logging to
make it more 'structured'.

* Update documentation on conversation api.

* Update go.mod and go.sum for new deps

* Update go.mod to version 0.7.0 of terraform-plugin-log

* added newline

* Made changes to satisfy pedantic linter.

* Address pedantic docs linter whitespace issues.

* Fix test failures
- some channel types (notably private ones) can't be joined.
- ephemeral attributes shouldn't be checked

docs/resources/conversation.md

@@ -11,14 +11,30 @@ Manages a Slack channel
 
 This resource requires the following scopes:
 
+If using `bot` tokens:
+
+- [channels:read](https://api.slack.com/scopes/channels:read)
+(public channels)
+- [channels:manage](https://api.slack.com/scopes/channels:manage)
+(public channels)
+- [channels:join](https://api.slack.com/scopes/channels:join)
+(adopting existing public channels)
+- [groups:read](https://api.slack.com/scopes/groups:read)
+(private channels)
+- [groups:write](https://api.slack.com/scopes/groups:write)
+(private channels)
+
+If using `user` tokens:
+
 - [channels:read](https://api.slack.com/scopes/channels:read) (public channels)
-- [channels:manage](https://api.slack.com/scopes/channels:manage) (public channels)
+- [channels:write](https://api.slack.com/scopes/channels:manage) (public channels)
 - [groups:read](https://api.slack.com/scopes/groups:read) (private channels)
 - [groups:write](https://api.slack.com/scopes/groups:write) (private channels)
 
 The Slack API methods used by the resource are:
 
 - [conversations.create](https://api.slack.com/methods/conversations.create)
+- [conversations.join](https://api.slack.com/methods/conversations.join)
 - [conversations.setTopic](https://api.slack.com/methods/conversations.setTopic)
 - [conversations.setPurpose](https://api.slack.com/methods/conversations.setPurpose)
 - [conversations.info](https://api.slack.com/methods/conversations.info)
@@ -53,6 +69,16 @@ resource "slack_conversation" "nonadmin" {
 }
 ```
 
+```hcl
+resource "slack_conversation" "adopted" {
+  name                               = "my-channel02"
+  topic                              = "Adopt existing, don't kick members"
+  permanent_members                  = []
+  adopt_existing_channel             = true
+  action_on_update_permanent_members = "none"
+}
+```
+
 ## Argument Reference
 
 The following arguments are supported:
@@ -72,6 +98,11 @@ name  will fail.
 whether the members should be kick of the channel when removed from
 `permanent_members`. When set to `none` the user are never kicked, this prevent
  a side effect on public channels where user that joined the channel are kicked.
+- `adopt_existing_channel` (Optional, Default `false`) indicates that an
+existing channel with the same name should be adopted by terraform and put under
+state management. If the existing channel is archived, it will be unarchived.
+(Note: for unarchiving of existing channels to work correctly, you_must_ use
+a user token, not a bot token, due to bugs in the Slack API)
 
 ## Attribute Reference
 

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/bflad/tfproviderdocs v0.9.1
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/go-multierror v1.1.1
+	github.com/hashicorp/terraform-plugin-log v0.7.0 // indirect
 	github.com/hashicorp/terraform-plugin-sdk/v2 v2.20.0
 	github.com/katbyte/terrafmt v0.5.2
 	github.com/mitchellh/cli v1.1.2 // indirect

go.sum

@@ -146,6 +146,7 @@ github.com/envoyproxy/go-control-plane v0.9.9-0.20210512163311-63b5d3c536b0/go.m
 github.com/envoyproxy/go-control-plane v0.9.10-0.20210907150352-cf90f659a021/go.mod h1:AFq3mo9L8Lqqiid3OhADV3RfLJnjiw63cSpi+fDTRC0=
 github.com/envoyproxy/go-control-plane v0.10.2-0.20220325020618-49ff273808a1/go.mod h1:KJwIaB5Mv44NWtYuAOFCVOjcI94vtpEz2JU/D2v6IjE=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
+github.com/fatih/color v1.7.0 h1:DkWD4oS2D8LGGgTQ6IvwJJXSL5Vp2ffcQg58nFV38Ys=
 github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5KwzbycvMj4=
 github.com/fatih/color v1.9.0/go.mod h1:eQcE1qtQxscV5RaZvpXrrb8Drkc3/DdQ+uUYCNjL+zU=
 github.com/fatih/color v1.13.0 h1:8LOYc1KYPPmyKMuN8QV2DNRWNbLo6LZ0iLs8+mlH53w=
@@ -316,6 +317,7 @@ github.com/hashicorp/hc-install v0.4.0 h1:cZkRFr1WVa0Ty6x5fTvL1TuO1flul231rWkGH9
 github.com/hashicorp/hc-install v0.4.0/go.mod h1:5d155H8EC5ewegao9A4PUTMNPZaq+TbOzkJJZ4vrXeI=
 github.com/hashicorp/hcl v1.0.0 h1:0Anlzjpi4vEasTeNFn2mLJgTSwt0+6sfsiTG8qcWGx4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
+github.com/hashicorp/hcl/v2 v2.6.0/go.mod h1:bQTN5mpo+jewjJgh8jr0JUguIi7qPHUF6yIfAEN3jqY=
 github.com/hashicorp/hcl/v2 v2.13.0 h1:0Apadu1w6M11dyGFxWnmhhcMjkbAiKCv7G1r/2QgCNc=
 github.com/hashicorp/hcl/v2 v2.13.0/go.mod h1:e4z5nxYlWNPdDSNYX+ph14EvWYMFm3eP0zIUqPc2jr0=
 github.com/hashicorp/logutils v1.0.0 h1:dLEQVugN8vlakKOUE3ihGLTZJRB4j+M2cdTm/ORI65Y=
@@ -327,8 +329,11 @@ github.com/hashicorp/serf v0.9.7/go.mod h1:TXZNMjZQijwlDvp+r0b63xZ45H7JmCmgg4gpT
 github.com/hashicorp/terraform-exec v0.17.2 h1:EU7i3Fh7vDUI9nNRdMATCEfnm9axzTnad8zszYZ73Go=
 github.com/hashicorp/terraform-exec v0.17.2/go.mod h1:tuIbsL2l4MlwwIZx9HPM+LOV9vVyEfBYu2GsO1uH3/8=
 github.com/hashicorp/terraform-json v0.5.0/go.mod h1:eAbqb4w0pSlRmdvl8fOyHAi/+8jnkVYN28gJkSJrLhU=
+github.com/hashicorp/terraform-json v0.8.0/go.mod h1:3defM4kkMfttwiE7VakJDwCd4R+umhSQnvJwORXbprE=
 github.com/hashicorp/terraform-json v0.14.0 h1:sh9iZ1Y8IFJLx+xQiKHGud6/TSUCM0N8e17dKDpqV7s=
 github.com/hashicorp/terraform-json v0.14.0/go.mod h1:5A9HIWPkk4e5aeeXIBbkcOvaZbIYnAIkEyqP2pNSckM=
+github.com/hashicorp/terraform-plugin-go v0.9.1 h1:vXdHaQ6aqL+OF076nMSBV+JKPdmXlzG5mzVDD04WyPs=
+github.com/hashicorp/terraform-plugin-go v0.9.1/go.mod h1:ItjVSlQs70otlzcCwlPcU8FRXLdO973oYFRZwAOxy8M=
 github.com/hashicorp/terraform-plugin-go v0.12.0 h1:6wW9mT1dSs0Xq4LR6HXj1heQ5ovr5GxXNJwkErZzpJw=
 github.com/hashicorp/terraform-plugin-go v0.12.0/go.mod h1:kwhmaWHNDvT1B3QiSJdAtrB/D4RaKSY/v3r2BuoWK4M=
 github.com/hashicorp/terraform-plugin-log v0.6.0/go.mod h1:p4R1jWBXRTvL4odmEkFfDdhUjHf9zcs/BCoNHAc7IK4=
@@ -397,13 +402,15 @@ github.com/magiconair/properties v1.8.6 h1:5ibWZ6iY0NctNGWo87LalDlEZ6R41TqbbDamh
 github.com/magiconair/properties v1.8.6/go.mod h1:y3VJvCyxH9uVvJTWEGAELF3aiYNyPKd5NZ3oSwXrF60=
 github.com/matryer/is v1.2.0/go.mod h1:2fLPjFQM9rhQ15aVEtbuwhJinnOqrmgXPNdZsdwlWXA=
 github.com/mattn/go-colorable v0.0.9/go.mod h1:9vuHe8Xs5qXnSaW/c/ABM9alt+Vo+STaOChaDxuIBZU=
+github.com/mattn/go-colorable v0.1.4 h1:snbPLB8fVfU9iwbbo30TPtbLRzwWu6aJS6Xh4eaaviA=
 github.com/mattn/go-colorable v0.1.4/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
 github.com/mattn/go-colorable v0.1.6/go.mod h1:u6P/XSegPjTcexA+o6vUJrdnUu04hMope9wVRipJSqc=
 github.com/mattn/go-colorable v0.1.9/go.mod h1:u6P/XSegPjTcexA+o6vUJrdnUu04hMope9wVRipJSqc=
 github.com/mattn/go-colorable v0.1.12 h1:jF+Du6AlPIjs2BiUiQlKOX0rt3SujHxPnksPKZbaA40=
 github.com/mattn/go-colorable v0.1.12/go.mod h1:u5H1YNBxpqRaxsYJYSkiCWKzEfiAb1Gb520KVy5xxl4=
 github.com/mattn/go-isatty v0.0.3/go.mod h1:M+lRXTBqGeGNdLjl/ufCoiOlB5xdOkqRJdNxMWT7Zi4=
 github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
+github.com/mattn/go-isatty v0.0.10 h1:qxFzApOv4WsAL965uUPIsXzAKCZxN2p9UqdhFS4ZW10=
 github.com/mattn/go-isatty v0.0.10/go.mod h1:qgIWMr58cqv1PHHyhnkY9lrL7etaEgOFcMEpPG5Rm84=
 github.com/mattn/go-isatty v0.0.11/go.mod h1:PhnuNfih5lzO57/f3n+odYbM4JtupLOxQOAqxQCu2WE=
 github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
@@ -560,6 +567,7 @@ github.com/zclconf/go-cty v1.1.0/go.mod h1:xnAOWiHeOqg2nWS62VtQ7pbOu17FtxJNW8RLE
 github.com/zclconf/go-cty v1.2.0/go.mod h1:hOPWgoHbaTUnI5k4D2ld+GRpFJSCe6bCM7m1q/N4PQ8=
 github.com/zclconf/go-cty v1.2.1/go.mod h1:hOPWgoHbaTUnI5k4D2ld+GRpFJSCe6bCM7m1q/N4PQ8=
 github.com/zclconf/go-cty v1.8.0/go.mod h1:vVKLxnk3puL4qRAv72AO+W99LUD4da90g3uUAzyuvAk=
+github.com/zclconf/go-cty v1.9.1/go.mod h1:vVKLxnk3puL4qRAv72AO+W99LUD4da90g3uUAzyuvAk=
 github.com/zclconf/go-cty v1.10.0 h1:mp9ZXQeIcN8kAwuqorjH+Q+njbJKjLrvB2yIh4q7U+0=
 github.com/zclconf/go-cty v1.10.0/go.mod h1:vVKLxnk3puL4qRAv72AO+W99LUD4da90g3uUAzyuvAk=
 github.com/zclconf/go-cty-debug v0.0.0-20191215020915-b22d67c1ba0b/go.mod h1:ZRKQfBXbGkpdV6QMzT3rU1kSTAnfu1dO8dPKjYprgj8=
@@ -807,6 +815,7 @@ golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.4/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.5/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=

slack/resource_conversation.go

@@ -3,7 +3,9 @@ package slack
 import (
 	"context"
 	"fmt"
+	"time"
 
+	"github.com/hashicorp/terraform-plugin-log/tflog"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/validation"
@@ -16,6 +18,10 @@ const (
 
 	conversationActionOnUpdatePermanentMembersNone = "none"
 	conversationActionOnUpdatePermanentMembersKick = "kick"
+
+	// 100 is default, slack docs recommend no more than 200, but 1000 is the max.
+	// See also https://github.com/slack-go/slack/blob/master/users.go#L305
+	cursorLimit = 200
 )
 
 var (
@@ -112,6 +118,11 @@ func resourceSlackConversation() *schema.Resource {
 				Default:      "kick",
 				ValidateFunc: validateConversationActionOnUpdatePermanentMembers,
 			},
+			"adopt_existing_channel": {
+				Type:     schema.TypeBool,
+				Optional: true,
+				Default:  false,
+			},
 		},
 	}
 }
@@ -123,6 +134,17 @@ func resourceSlackConversationCreate(ctx context.Context, d *schema.ResourceData
 	isPrivate := d.Get("is_private").(bool)
 
 	channel, err := client.CreateConversationContext(ctx, name, isPrivate)
+	if err != nil && err.Error() == "name_taken" && d.Get("adopt_existing_channel").(bool) {
+		channel, err = findExistingChannel(ctx, client, name, isPrivate)
+		if err == nil && channel.IsArchived {
+			// ensure unarchived first if adopting existing channel, else other calls below will fail
+			if err := client.UnArchiveConversationContext(ctx, channel.ID); err != nil {
+				if err.Error() != "not_archived" {
+					return diag.Errorf("couldn't unarchive conversation %s: %s", channel.ID, err)
+				}
+			}
+		}
+	}
 	if err != nil {
 		return diag.Errorf("could not create conversation %s: %s", name, err)
 	}
@@ -157,6 +179,58 @@ func resourceSlackConversationCreate(ctx context.Context, d *schema.ResourceData
 	return resourceSlackConversationRead(ctx, d, m)
 }
 
+func findExistingChannel(ctx context.Context, client *slack.Client, name string, isPrivate bool) (*slack.Channel, error) {
+	// find the existing channel. Sadly, there is no non-admin API to search by name,
+	// so we must search through ALL the channels
+	tflog.Info(ctx, "Looking for channel %s", map[string]interface{}{"channel": name})
+	paginationComplete := false
+	cursor := ""       // initial empty cursor to begin at start of list
+	var types []string // default value with empty list is "public_channel"
+	if isPrivate {
+		types = append(types, "private_channel")
+	}
+	for !paginationComplete {
+		channels, nextCursor, err := client.GetConversationsContext(ctx, &slack.GetConversationsParameters{
+			Cursor: cursor,
+			Limit:  cursorLimit,
+			Types:  types,
+		})
+		tflog.Debug(ctx, "new page of channels",
+			map[string]interface{}{
+				"numChannels": len(channels),
+				"nextCursor":  nextCursor,
+				"err":         err})
+		if err != nil {
+			if rateLimitedError, ok := err.(*slack.RateLimitedError); ok {
+				tflog.Warn(ctx, "rate limited", map[string]interface{}{"seconds": rateLimitedError.RetryAfter.Seconds()})
+				select {
+				case <-ctx.Done():
+					return nil, fmt.Errorf("canceled during pagination: %s", ctx.Err())
+				case <-time.After(rateLimitedError.RetryAfter):
+					tflog.Debug(ctx, "done sleeping after rate limited")
+				}
+				// retry current cursor
+			} else {
+				return nil, fmt.Errorf("name_taken, but %s trying to find", err)
+			}
+		} else {
+			// see if channel in current batch
+			for _, c := range channels {
+				tflog.Trace(ctx, "checking channel", map[string]interface{}{"channel": c.Name})
+				if c.Name == name {
+					tflog.Info(ctx, "found channel")
+					return &c, nil
+				}
+			}
+			// not found so far, move on to next cursor, if pagination incomplete
+			paginationComplete = nextCursor == ""
+			cursor = nextCursor
+		}
+	}
+	// looked through entire list, but didn't find matching name
+	return nil, fmt.Errorf("name_taken, but could not find channel")
+}
+
 func updateChannelMembers(ctx context.Context, d *schema.ResourceData, client *slack.Client, channelID string) error {
 	members := d.Get("permanent_members").(*schema.Set)
 
@@ -182,6 +256,13 @@ func updateChannelMembers(ctx context.Context, d *schema.ResourceData, client *s
 		return fmt.Errorf("could not retrieve conversation users for ID %s: %w", channelID, err)
 	}
 
+	// first, ensure the api user is in the channel, otherwise other member modifications below may fail
+	if _, _, _, err := client.JoinConversationContext(ctx, channelID); err != nil {
+		if err.Error() != "already_in_channel" && err.Error() != "method_not_supported_for_channel_type" {
+			return fmt.Errorf("api user could not join conversation: %w", err)
+		}
+	}
+
 	action := d.Get("action_on_update_permanent_members").(string)
 	if action == conversationActionOnUpdatePermanentMembersKick {
 		for _, currentMember := range channelUsers {
@@ -265,7 +346,7 @@ func resourceSlackConversationUpdate(ctx context.Context, d *schema.ResourceData
 		} else {
 			if err := client.UnArchiveConversationContext(ctx, id); err != nil {
 				if err.Error() != "not_archived" {
-					return diag.Errorf("couldn't archive conversation %s: %s", id, err)
+					return diag.Errorf("couldn't unarchive conversation %s: %s", id, err)
 				}
 			}
 		}

slack/resource_conversation_test.go

@@ -144,7 +144,7 @@ func testSlackConversationUpdate(t *testing.T, resourceName string, createChanne
 			ResourceName:            resourceName,
 			ImportState:             true,
 			ImportStateVerify:       true,
-			ImportStateVerifyIgnore: []string{"permanent_members", "action_on_destroy", "action_on_update_permanent_members"},
+			ImportStateVerifyIgnore: []string{"permanent_members", "action_on_destroy", "action_on_update_permanent_members", "adopt_existing_channel"},
 		},
 	}