Unable to post messages when in deployment

[isidhux]

What happened

I am integrating slack with an application. while running code with 'go test', everything is working fine, but once i deploy the app in docker container after generating a build, it is throwing the following error:

"Post "https://slack.com/api/chat.postMessage\": tls: failed to verify certificate: x509: certificate signed by unknown authority"

Expected behavior

It should send the messages

Steps to reproduce

generate a build and run the binary in ubuntu:latest docker container
i am using docker compose to run the app and redis container
use the code from slack-go tutorial https://medium.com/@wambuirebeka/how-to-integrate-slack-notifications-using-golang-84451aca27e3#:~:text=New()%20New%20builds%20a,the%20provided%20token%20and%20options.&text=Our%20func%20sendSlackMessage%20takes%20in,a%20message%20to%20a%20channel.

reproducible code

type Slack struct {
SlackClient *slack.Client
ChannelID string
}

func (s *Slack) SendSlackMessage(message string) error {
ChannelID, timestamp, err := s.SlackClient.PostMessage(s.ChannelID, slack.MsgOptionText(message, false))
if err != nil {
return err
}
fmt.Printf("Message sent successfully to %s channel at %s\n", ChannelID, timestamp)
return nil
}

slackObj := &Slack{
SlackClient: slack.New("token-string"),
ChannelID: "channel-id",
}
if err := slackObj.SendSlackMessage("Vcenter Sync Failed"); err != nil {
t.Fatalf("Error occured while sending slack msg: %v \n", err)
}

Versions

• Go: go1.21.5 linux/amd64
• slack-go/slack: 0.12.5

[isidhux]

executes without problem in host machine, but gives problem when deployed to container