Try_files directive in Nginx - Step-by-Step Execution

Process Flow - Try_files directive

Request comes in

↓

Try first file

↓

Serve file

No↓

Try second file

↓

Serve file

No↓

Fallback URI

↓

Serve fallback or error

The try_files directive checks files in order and serves the first existing one, or falls back to a URI if none exist.

Execution Sample

Nginx

location / {
  try_files $uri $uri/ /index.html;
}

This tries to serve the requested URI as a file, then as a directory, then falls back to /index.html.

Process Table

Step	Requested URI	File Checked	Exists?	Action
1	/about	/about	No	Try next file
2	/about	/about/	No	Try next file
3	/about	/index.html	Yes	Serve /index.html
4	END	-	-	Request served, stop

💡 Stopped after serving /index.html fallback because previous files did not exist.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
$uri	/about	/about	/about	/about	/about
File Checked	-	/about	/about/	/index.html	/index.html
Exists?	-	No	No	Yes	Yes
Action	-	Try next	Try next	Serve file	Serve file

Key Moments - 2 Insights

Why does nginx try multiple files instead of serving the first one it checks?

Because try_files checks each file in order and only serves the first one that exists. If a file doesn't exist, it moves to the next (see execution_table steps 1 and 2).

What happens if none of the files exist?

Nginx serves the fallback URI specified last in try_files, like /index.html in the example (see execution_table step 3).

Visual Quiz - 3 Questions

Look at the execution table, what file does nginx serve at step 3?

A /index.html

B /about/

C /about

D No file served

💡 Hint

Check the 'File Checked' and 'Action' columns at step 3 in the execution_table.

At which step does nginx find an existing file to serve?

A Step 1

B Step 3

C Step 2

D No step, it never finds a file

💡 Hint

Look at the 'Exists?' column in the execution_table to see when it becomes 'Yes'.

If /about existed as a file, how would the execution table change?

A Nginx would still check /about/ and /index.html

B Nginx would serve /index.html anyway

C Step 1 'Exists?' would be Yes and nginx would serve /about immediately

D The fallback URI would be served first

💡 Hint

Try_files stops at the first existing file, see execution_table step 1 for current behavior.

Concept Snapshot

try_files directive syntax:
try_files file1 file2 ... fallback_uri;

Checks each file in order.
Serves the first existing file.
If none exist, serves fallback URI.
Useful for clean URLs and SPA fallback.

Full Transcript

The try_files directive in nginx processes a request by checking a list of files in order. It tries to find the first file that exists on the server matching the requested URI or alternatives. If it finds one, it serves that file immediately. If none of the files exist, it serves a fallback URI, often used to serve a default page like index.html. This behavior helps handle requests for static files, directories, or fallback pages in a clean and efficient way.