How to Prevent Selenium 3.0 (Geckodriver) from Creating Temporary Firefox Profiles?

Question

I'm running the latest version of Selenium WebDriver with Geckodriver. I want to prevent Selenium from creating temporary Firefox Profiles in the temporary files directory when launching a new instance of WebDriver. Instead I want to use the original Firefox Profile directly. This has double benefit. First, it saves time (it takes significant amount of time for the profile to be copied to the temporary directory). Second, it ensures that cookies created during session are saved to the original profile. Before Selenium started relying on Geckodriver I was able to solve this problem by editing the class FirefoxProfile.class in SeleniumHQ as seen below:

public File layoutOnDisk() {

 File profileDir;

 if (this.disableTempProfileCreation) {
  profileDir = this.model;
  return profileDir;

  } else {

   try {
    profileDir = TemporaryFilesystem.getDefaultTmpFS().createTempDir("ABC", "XYZ");
    File userPrefs = new File(profileDir, "user.js");
    this.copyModel(this.model, profileDir);
    this.installExtensions(profileDir);
    this.deleteLockFiles(profileDir);
    this.deleteExtensionsCacheIfItExists(profileDir);
    this.updateUserPrefs(userPrefs);
    return profileDir;
    } catch (IOException var3) {
   throw new UnableToCreateProfileException(var3);
  }
 }
}

This would stop Selenium from creating a temporary Firefox Profile when the parameter disableTempProfileCreation was set to true.

However, now that Selenium is being controlled by Geckodriver this solution no longer works as the creation (and launch) of Firefox Profile is controlled by Geckodriver.exe (which is written in Rust language). How can I achieve the same objective with Geckodriver? I don't mind editing the source code. I'm using Java.

Thanks

Important Update:

I would like to thank everyone for taking the time to respond to this question. However, as stated in some of the comments, the first 3 answers do not address the question at all - for two reasons. First of all, using an existing Firefox Profile will not prevent Geckodriver from copying the original profile to a temporary directory (as indicated in the OP and clearly stated by one or more of the commentators below). Second, even if it did it is not compatible with Selenium 3.0.

I'm really not sure why 3 out of 4 answer repeat the exact same answer with the exact same mistake. Did they read the question? The only answer the even attempts to address the question at hand is the answer by @Life is complex however it is incomplete. Thanks.

Answer 1

UPDATED POST 05-30-2021

---

This is the hardest question that I have every tried to answer on Stack Overflow. Because it involved the interactions of several code bases written in multiple languages (Java, Rust and C++). This complexity made the question potentially unsolvable.

My last crack at this likely unsolvable question:

Within the code in your question you are modifying the file user.js This file is still used by Selenium.

public FirefoxProfile() {
    this(null);
  }

  /**
   * Constructs a firefox profile from an existing profile directory.
   * <p>
   * Users who need this functionality should consider using a named profile.
   *
   * @param profileDir The profile directory to use as a model.
   */
  public FirefoxProfile(File profileDir) {
    this(null, profileDir);
  }

  @Beta
  protected FirefoxProfile(Reader defaultsReader, File profileDir) {
    if (defaultsReader == null) {
      defaultsReader = onlyOverrideThisIfYouKnowWhatYouAreDoing();
    }

    additionalPrefs = new Preferences(defaultsReader);

    model = profileDir;
    verifyModel(model);

    File prefsInModel = new File(model, "user.js");
    if (prefsInModel.exists()) {
      StringReader reader = new StringReader("{\"frozen\": {}, \"mutable\": {}}");
      Preferences existingPrefs = new Preferences(reader, prefsInModel);
      acceptUntrustedCerts = getBooleanPreference(existingPrefs, ACCEPT_UNTRUSTED_CERTS_PREF, true);
      untrustedCertIssuer = getBooleanPreference(existingPrefs, ASSUME_UNTRUSTED_ISSUER_PREF, true);
      existingPrefs.addTo(additionalPrefs);
    } else {
      acceptUntrustedCerts = true;
      untrustedCertIssuer = true;
    }

    // This is not entirely correct but this is not stored in the profile
    // so for now will always be set to false.
    loadNoFocusLib = false;

    try {
      defaultsReader.close();
    } catch (IOException e) {
      throw new WebDriverException(e);
    }
  }

So in theory you should be able to modify capabilities.rs in the geckodriver source code. That file contains the temp_dir.

As I stated this in only a theory, because when I looked at the Firefox source, which has temp_dir spread throughout the code base.

ORIGINAL POST 05-26-2021

---

I'm not sure that you can prevent Selenium from creating a temporary Firefox Profile.

From the gecko documents:

"Profiles are created in the systems temporary folder. This is also where the encoded profile is extracted when profile is provided. By default geckodriver will create a new profile in this location."

The only solution that I see at the moment would require you modify the Geckodriver source files to prevent the creation of temporary folders/profiles.

I'm currently looking at the source. These files might be the correct ones, but I need to look at the source more:

• https://searchfox.org/mozilla-central/source/browser/app/profile/firefox.js

• https://searchfox.org/mozilla-central/source/testing/mozbase/mozprofile/mozprofile/profile.py

Here are some other files that need to be combed through:

https://searchfox.org/mozilla-central/search?q=tempfile&path=

---

This looks promising:

https://searchfox.org/mozilla-central/source/testing/geckodriver/doc/Profiles.md

"geckodriver uses [profiles] to instrument Firefox’ behaviour. The user will usually rely on geckodriver to generate a temporary, throwaway profile. These profiles are deleted when the WebDriver session expires.

In cases where the user needs to use custom, prepared profiles, geckodriver will make modifications to the profile that ensures correct behaviour. See [Automation preferences] below on the precedence of user-defined preferences in this case.

Custom profiles can be provided two different ways:

1. by appending --profile /some/location to the [args capability], which will instruct geckodriver to use the profile in-place;

I found this question on trying to do this: how do I use an existing profile in-place with Selenium Webdriver?

Also here is an issue that was raised in selenium on Github concerning the temp directory. https://github.com/SeleniumHQ/selenium/issues/8645

---

Looking through the source of geckodriver v0.29.1 I found a file where the profile is loaded.

source: capabilities.rs

   fn load_profile(options: &Capabilities) -> WebDriverResult<Option<Profile>> {
        if let Some(profile_json) = options.get("profile") {
            let profile_base64 = profile_json.as_str().ok_or_else(|| {
                WebDriverError::new(ErrorStatus::InvalidArgument, "Profile is not a string")
            })?;
            let profile_zip = &*base64::decode(profile_base64)?;

            // Create an emtpy profile directory
            let profile = Profile::new()?;
            unzip_buffer(
                profile_zip,
                profile
                    .temp_dir
                    .as_ref()
                    .expect("Profile doesn't have a path")
                    .path(),
            )?;

            Ok(Some(profile))
        } else {
            Ok(None)
        }
    }

source: marionette.rs

    fn start_browser(&mut self, port: u16, options: FirefoxOptions) -> WebDriverResult<()> {
        let binary = options.binary.ok_or_else(|| {
            WebDriverError::new(
                ErrorStatus::SessionNotCreated,
                "Expected browser binary location, but unable to find \
             binary in default location, no \
             'moz:firefoxOptions.binary' capability provided, and \
             no binary flag set on the command line",
            )
        })?;

        let is_custom_profile = options.profile.is_some();

        let mut profile = match options.profile {
            Some(x) => x,
            None => Profile::new()?,
        };

        self.set_prefs(port, &mut profile, is_custom_profile, options.prefs)
            .map_err(|e| {
                WebDriverError::new(
                    ErrorStatus::SessionNotCreated,
                    format!("Failed to set preferences: {}", e),
                )
            })?;

        let mut runner = FirefoxRunner::new(&binary, profile);

        runner.arg("--marionette");
        if self.settings.jsdebugger {
            runner.arg("--jsdebugger");
        }
        if let Some(args) = options.args.as_ref() {
            runner.args(args);
        }

        // https://developer.mozilla.org/docs/Environment_variables_affecting_crash_reporting
        runner
            .env("MOZ_CRASHREPORTER", "1")
            .env("MOZ_CRASHREPORTER_NO_REPORT", "1")
            .env("MOZ_CRASHREPORTER_SHUTDOWN", "1");

        let browser_proc = runner.start().map_err(|e| {
            WebDriverError::new(
                ErrorStatus::SessionNotCreated,
                format!("Failed to start browser {}: {}", binary.display(), e),
            )
        })?;
        self.browser = Some(Browser::Host(browser_proc));

        Ok(())
    }

    pub fn set_prefs(
        &self,
        port: u16,
        profile: &mut Profile,
        custom_profile: bool,
        extra_prefs: Vec<(String, Pref)>,
    ) -> WebDriverResult<()> {
        let prefs = profile.user_prefs().map_err(|_| {
            WebDriverError::new(
                ErrorStatus::UnknownError,
                "Unable to read profile preferences file",
            )
        })?;

        for &(ref name, ref value) in prefs::DEFAULT.iter() {
            if !custom_profile || !prefs.contains_key(name) {
                prefs.insert((*name).to_string(), (*value).clone());
            }
        }

        prefs.insert_slice(&extra_prefs[..]);

        if self.settings.jsdebugger {
            prefs.insert("devtools.browsertoolbox.panel", Pref::new("jsdebugger"));
            prefs.insert("devtools.debugger.remote-enabled", Pref::new(true));
            prefs.insert("devtools.chrome.enabled", Pref::new(true));
            prefs.insert("devtools.debugger.prompt-connection", Pref::new(false));
        }

        prefs.insert("marionette.log.level", logging::max_level().into());
        prefs.insert("marionette.port", Pref::new(port));

        prefs.write().map_err(|e| {
            WebDriverError::new(
                ErrorStatus::UnknownError,
                format!("Unable to write Firefox profile: {}", e),
            )
        })
    }
}

After looking through the gecko source it looks like mozprofile::profile::Profile is coming from FireFox and not geckodriver

---

It seems that you might have issues with profiles when you migrate to Selenium 4.

ref: https://github.com/SeleniumHQ/selenium/issues/9417

For Selenium 4 we have deprecated the use of profiles as there are other mechanisms that we can do to make the start up faster. Please use the Options class to set preferences that you need and if you need to use an addon use the driver.install_addon("path/to/addon") you can install selenium 4, which is in beta, via pip install selenium --pre

---

I noted in your code you were writing to user.js, which is a custom file for FireFox. Have you considered creating on these files manually outside of Gecko?

Also have you looked at mozprofile?

Answer 2

Thanks to source code provided in answer of Life is complex in link!. I have the chance to look through geckodriver source.

EXPLANATION

I believe that the reason you could not find out any rust_tmp in source because it is generated randomly by Profile::new() function.

When I look deeper in code structure, I saw that browser.rs is the place where the browser is actually loaded which is called through marionette.rs. If you noticing carefully, LocalBrowser::new method will be called whenever a new session is initialized and the profile will be loaded in that state also. Then by checking browser.rs file, there will be a block code line 60 - 70 used to actually generate profile for new session instance. Now, what need to do is modifying this path to load your custom profile.

SHORT ANSWER

Downloading zip file of geckodriver-0.30.0, extracting it by your prefer zip program :P

Looking on src/browser.rs of geckodriver source, in line 60 - 70, hoping you will see something like this:

        let is_custom_profile = options.profile.is_some();

        let mut profile = match options.profile {
            Some(x) => x,
            None => Profile::new()?,
        };

Change it to your prefer folder ( hoping you know some rust code ), example:

        /*
        let mut profile = match options.profile {
            Some(x) => x,
            None => Profile::new()?,
        };
        */
        let path = std::path::Path::new("path-to-profile");
        let mut profile = Profile::new_from_path(path)?;

Re-compile with prefer rust compiler, example:

Cargo build

NOTE

Hoping this info will help you someway. This is not comprehensive but hoping it is good enough hint for you like it is possible to write some extra code to load profile from env or pass from argument, it is possible but I'm not rust developer so too lazy for providing one in here.

The above solution is work fine for me and I could load and use directly my profile from that. Btw, I work on Archlinux with rust info: cargo 1.57.0.

TBH, this is first time I push comment on stackoverflow, so feel free to correct me if I'm wrong or produce unclear answer :P

Update

1. I worked in geckodriver 0.30.0 which will not be the same as geckodriver 0.29.1 mentioned by Life is complex. But the change between 2 versions just be split action, so the similar modify path in version 0.29.1 will be included in method MarionetteHandler::start_browser in file src/marionette.rs.

2. Since my starting point is Life is complex answer, please looking through it for more information.