Psalm 30 is a praise psalm. But it sort of sounds like a lament psalm.
In this Psalm we see David relate how his own pride seemed to bring God’s fearful chastening – which he says almost killed him. But the Lord was merciful and so David praises him for that mercy.
So, not only does the content of Psalm 30 indicate that it’s a praise psalm – but the structure of the psalm also indicates that it’s a praise psalm.
We have verse 1 that begins with the call to praise – “I will extol thee, O LORD.” (KJV) Then we have the typical catalog of praiseworthy attributes or actions of the Lord that serves as the body of the psalm. And then the psalm ends with this typical concluding praise – “O LORD my God, I will give thanks unto thee for ever.”
So, both the content and the structure of Psalm 30 let us know that we’re reading a praise psalm.