【Azure 应用服务】Storage Queue触发Azure Function时报错 The input is not a valid Base64 string

问题描述

创建一个PowerShell脚本的Azure Function，触发方式为 Storage Queue。但执行函数结果一直失败 (Failed).

错误消息为：

Executed 'Functions.QueueTrigger1' (Failed, Id=..., Duration=30ms) The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.

Funciton 代码：

# Input bindings are passed in via param block.
param([string] $QueueItem, $TriggerMetadata)

# Write out the queue message and metadata to the information log.
Write-Host "PowerShell queue trigger function processed work item: $QueueItem"
Write-Host "Queue item expiration time: $($TriggerMetadata.ExpirationTime)"
Write-Host "Queue item insertion time: $($TriggerMetadata.InsertionTime)"
Write-Host "Queue item next visible time: $($TriggerMetadata.NextVisibleTime)"
Write-Host "ID: $($TriggerMetadata.Id)"
Write-Host "Pop receipt: $($TriggerMetadata.PopReceipt)"
Write-Host "Dequeue count: $($TriggerMetadata.DequeueCount)"

通过向Storage Queue中添加消息时候触发：

az storage message put --content "This is a function test message" 

问题分析

根据错误消息，Function (Storage Queue）触发的消息需要 Base64编码，如发送 "This is a function test message"  这段消息，需要在发送消息时候转换为base64编码。

在CMD中调用PowerShell进行类型转换：

powershell "[convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes(\"This is a function test message\"))"

在Powershell中直接转换：

[convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes("This is a function test message"))

所以，修改后的向Storage Queue中添加消息的命令为：

$queuemsg = [convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes("This is a function test message"))

az storage message put --content $queuemsg 

参考资料

适用于 Azure Functions 的 Azure 队列存储触发器： https://docs.azure.cn/zh-cn/azure-functions/functions-bindings-storage-queue-trigger?tabs=powershell#encoding